[N0OS3]

My suggestion if you want to put headers in with straight pipe, i'd fool around with Magnaflow mufflers to start off. My theory is that since there is a lot of oldschool muscle cars without cats in the headers and it's common to have them cut out and a nice muffler put in place to get a nice low frequency tone. And as said above, you need some back pressure to keep your torque curve in the same place but you need a more free-flowing exhaust to get gains.

When i cut out my muffler, rez, and s. cats, i noticed my car was a little bit more 'jumpy' but the power was lost over 5500rpm... my conclusion was that i moved my power to the lower rpms vice just adding horsepower. So, once i get these headers in i'll get on the dyno and do some runs... but that'll be a while so i don't suggest keeping track of my posts lol

[SR2007]

Originally Posted by speedfan

hahaha lync9763, that was me!
It's Eisenmann Race btw.



SR2001,
I dont think running straight pipe + headers will give you any gain.
I even think that you'll lose some low end torque.
I doubt that you'd get any gain on the top-end. Even if you did, I don't think you'd dare to get up there in the high rpm range without attracting unwanted attention.

My car's a 325i 2.5L engine (euro model), I've tried pretty much everything with the exhaust setup.
at 1 point, I've had Supersprint headers, straight pipes with no cats, no resonator, & Eisenmann Race rear muffler.
& the car got very raspy & unbearable loud. It was too loud that I wouldn't dare to get up to 4k rpm without scaring dogs & cats.

Check out my review here: http://www.e90post.com/forums/showthread.php?t=593522

if you insist of getting the headers, my suggestion is:
- headers + straight pipes (no cats, no resonator) + CUSTOM muffler to reduce the loudness & to play around with backpressure. You need backpressure.

Too much free flow isn't good at all. You think you'd get some gain, that's probably a placebo effect.
If deleting everything giving some hp gain, thousands of people would've probably opened up shops & started competing with Eisenmann & Arkrapovic already.

Having said that, do post your dyno result before & after for the rest of us if you go down this path though.

You make some valid points. Some of the article I've read regarding back pressure in the BMW isn't necessary. Stated that free flow is actually better. Ill have to find the article again and post it.

Poeple just can't delete their cats. Its a federal law and up to 5g's per cat to cut off. Regardless of emissions laws per state, its federally mandated to maintain those cats for pollution purposes. Just so happens that non-emission states dont check. Then again its what your trying to accomplish. Many drag cars run nothing at all. Not just for weight, but more air flow is better.

I will try to coordinate my install with a dyno run pre an after tho for sure, for personal curiosity too.
I saw your post and vids, and it didn't sound all that bad. I actually like the raspy raw sound. I think it has more of an exotic aggressive appeal.
I want to run a true dual set-up, trying to figure a way to add in a second muffler to achieve that if I run muffs. Def not paying a G plus for a muffler from Hies, or anyone else for that matter. If I had an M...... I could justify that.

Got any ideas on what kind of mufflers?

[SR2007]

Originally Posted by lync9763

My suggestion if you want to put headers in with straight pipe, i'd fool around with Magnaflow mufflers to start off. My theory is that since there is a lot of oldschool muscle cars without cats in the headers and it's common to have them cut out and a nice muffler put in place to get a nice low frequency tone. And as said above, you need some back pressure to keep your torque curve in the same place but you need a more free-flowing exhaust to get gains.

When i cut out my muffler, rez, and s. cats, i noticed my car was a little bit more 'jumpy' but the power was lost over 5500rpm... my conclusion was that i moved my power to the lower rpms vice just adding horsepower. So, once i get these headers in i'll get on the dyno and do some runs... but that'll be a while so i don't suggest keeping track of my posts lol

Huh, all the the research that I did shows otherwise..... Looks like I need to do some more digging around. After careful thought it looks like Im gonna want a muffler just to keep the noise under control. But then again, has anyone tried just putting the res back into play with this set-up? I like the loud raspy tone. Give it more of an exotic aggressiveness I think.

Hey Im still deployed and wont be back for another three months roughly. You got time . lol

Like i mentioned before, I want to run a true duel set-up. Trying to figure out a way to incorportate the second muffler if i decided to add one in. Unless I can remove the luggage area compartment in the middle and run a 2 in and 2 out muff in the center. Just have to branch out the pipes for exit..........

[speedfan]

Originally Posted by SR2007

You make some valid points. Some of the article I've read regarding back pressure in the BMW isn't necessary. Stated that free flow is actually better. Ill have to find the article again and post it.

Poeple just can't delete their cats. Its a federal law and up to 5g's per cat to cut off. Regardless of emissions laws per state, its federally mandated to maintain those cats for pollution purposes. Just so happens that non-emission states dont check. Then again its what your trying to accomplish. Many drag cars run nothing at all. Not just for weight, but more air flow is better.

I will try to coordinate my install with a dyno run pre an after tho for sure, for personal curiosity too.
I saw your post and vids, and it didn't sound all that bad. I actually like the raspy raw sound. I think it has more of an exotic aggressive appeal.
I want to run a true dual set-up, trying to figure a way to add in a second muffler to achieve that if I run muffs. Def not paying a G plus for a muffler from Hies, or anyone else for that matter. If I had an M...... I could justify that.

Got any ideas on what kind of mufflers?

Originally Posted by SR2007

Huh, all the the research that I did shows otherwise..... Looks like I need to do some more digging around. After careful thought it looks like Im gonna want a muffler just to keep the noise under control. But then again, has anyone tried just putting the res back into play with this set-up? I like the loud raspy tone. Give it more of an exotic aggressiveness I think.

Hey Im still deployed and wont be back for another three months roughly. You got time . lol

Like i mentioned before, I want to run a true duel set-up. Trying to figure out a way to incorportate the second muffler if i decided to add one in. Unless I can remove the luggage area compartment in the middle and run a 2 in and 2 out muff in the center. Just have to branch out the pipes for exit..........

if you run headers + resonator, you might get the horrible rattles/vibrations that some of us have/had in my review thread. The cause is from the resonator. So, do some research of what resonator you're gonna put on.

I dont know any rear muffler to go with the headers. Plus, my goal is different than yours. So, I can't recommend any.

Garvin MMW mentioned a couple of rear mufflers in his headers thread, if you're gonna get the headers from him, you should check with him.
Or check with those tuners who build race BMW's.

Good luck & report back with your findings.
D

[Route 16]

What is your goal Dung?

Originally Posted by speedfan

if you run headers + resonator, you might get the horrible rattles/vibrations that some of us have/had in my review thread. The cause is from the resonator. So, do some research of what resonator you're gonna put on.

I dont know any rear muffler to go with the headers. Plus, my goal is different than yours. So, I can't recommend any.

Garvin MMW mentioned a couple of rear mufflers in his headers thread, if you're gonna get the headers from him, you should check with him.
Or check with those tuners who build race BMW's.

Good luck & report back with your findings.
D

[speedfan]

Originally Posted by yoko kai

What is your goal Dung?

Hey Jason,
My goal at the time was to get the most NA hp with bolt-on mods, but still retain its daily driving capability, i.e. not too loud.

I was gonna do: headers, Eisenmann race rear muffler, & a custome tune from ESS.
I got the first 2 down, & was about to get the tune. However, as you know, i couldn't live with the raspy & loudness the combo provided, so I gave up.

Then, I thought about a supercharger & a big brake kit, Thats like $16 - $20k, but quickly gave that up as well with the whole ARMA thing.

I think at this point, I will just save up my money for a better car. We will have a lot of options in the next couple of years Jason.

[SR2007]

Originally Posted by speedfan

Hey Jason,
My goal at the time was to get the most NA hp with bolt-on mods, but still retain its daily driving capability, i.e. not too loud.

I was gonna do: headers, Eisenmann race rear muffler, & a custome tune from ESS.
I got the first 2 down, & was about to get the tune. However, as you know, i couldn't live with the raspy & loudness the combo provided, so I gave up.

Then, I thought about a supercharger & a big brake kit, Thats like $16 - $20k, but quickly gave that up as well with the whole ARMA thing.

I think at this point, I will just save up my money for a better car. We will have a lot of options in the next couple of years Jason.

Hey from my understand MMW is a stone throw away from releasing a turbo or sc kit for our cars. Not 100% clear on which one, the form talks the gain is suppose to be outstanding. I think the price is really set to move too. Im eager to see the results and if its under 5g's Im in for sure.

Since you removed the headers, did you end up keeping your exhaust on? What are you doing with the headers?

[speedfan]

Originally Posted by SR2007

Hey from my understand MMW is a stone throw away from releasing a turbo or sc kit for our cars. Not 100% clear on which one, the form talks the gain is suppose to be outstanding. I think the price is really set to move too. Im eager to see the results and if its under 5g's Im in for sure.

Since you removed the headers, did you end up keeping your exhaust on? What are you doing with the headers?

I sold the headers to a gentleman from the States.

My car now is running stock headers, straight pipes (no resonator, no 2nd cats since its a Euro version), & Eisenmann race rear muffler, & I LOVE the sound the system makes.

Well, im quite content with the car now & probably not doing anything else but saving $ for another car. We'll see.

[Route 16]

Have you made a new sound clip of your current set up? Since you know I'm planning to change my pipes to make it sound louder, I just hope I'm not losing some low end torque. Just wondering if that happened to you or if it feels the same.

Originally Posted by speedfan

I sold the headers to a gentleman from the States.

My car now is running stock headers, straight pipes (no resonator, no 2nd cats since its a Euro version), & Eisenmann race rear muffler, & I LOVE the sound the system makes.

Well, im quite content with the car now & probably not doing anything else but saving $ for another car. We'll see.

[speedfan]

Yes I did buddy.
Here it is again in case you missed it.

Originally Posted by yoko kai

Have you made a new sound clip of your current set up? Since you know I'm planning to change my pipes to make it sound louder, I just hope I'm not losing some low end torque. Just wondering if that happened to you or if it feels the same.

[Route 16]

Oright oright oriiiight!

Inspired again. Does it feel the same on the throttle when you had the resonator?

Originally Posted by speedfan

Yes I did buddy.
Here it is again in case you missed it.

[speedfan]

ahh Kevin Hart, laugh at my pain.
I was gonna buy his DVD, "but the way my bank account is setup. The $ is in the savings. it will take 3 days to transfer to the checking..."

jk hehe. Love his bank account joke. classic.

You seen Russell Peters show yet?

Regarding the exhaust setup, it's the same throttle response, just the sound is louder.
I wish there was a dyno machine here in VN so I could compare before & after.

Originally Posted by yoko kai

Oright oright oriiiight!

Inspired again. Does it feel the same on the throttle when you had the resonator?

[Route 16]

My coworker just mentioned him tonight, what's his movie title? I'll download it.

I'll dyno my set up next 2 weeks? Then I'll install Detail Addicts and compare the two. You gon learn today!

Originally Posted by speedfan

ahh Kevin Hart, laugh at my pain.
I was gonna buy his DVD, "but the way my bank account is setup. The $ is in the savings. it will take 3 days to transfer to the checking..."

jk hehe. Love his bank account joke. classic.

You seen Russell Peters show yet?

Regarding the exhaust setup, it's the same throttle response, just the sound is louder.
I wish there was a dyno machine here in VN so I could compare before & after.

[speedfan]

Originally Posted by yoko kai

My coworker just mentioned him tonight, what's his movie title? I'll download it.

I'll dyno my set up next 2 weeks? Then I'll install Detail Addicts and compare the two. You gon learn today!

hahahah oright oright oriiiight.
the movie called: Kevin Hart Laugh At My Pain.

[Route 16]

I mean what's Russell Peter's movie called.

Originally Posted by speedfan

hahahah oright oright oriiiight.
the movie called: Kevin Hart Laugh At My Pain.

[speedfan]

Originally Posted by yoko kai

I mean what's Russell Peter's movie called.

Oh hehe. sorry about that.
Try: Outsourced (2006)
& Red, White, & Brown (2008).

[DylanMckay]

Originally Posted by yoko kai

So on the pipe below, where would you recommend making an x connection?

I do not know who's exhaust this is but those pipes are WAY too big. Every response on here is missing the only thing that actually matters which is exhaust velocity!

You want the absolutely most free flowing exhaust you can get with no backpressure BUT you need to maintain or improve the velocity of the gases to not lose power and perhaps gain a hp or two.

The larger diameter pipes with a 3.0 220hp engine does not produce enough gases to run at a high velocity which is why the OEM pipes are much smaller diameter which keeps the velocity and scavenging going properly. So many people mistakely call this "needing backpressure" when it is actually needing velocity which sometimes inevitibly causes some increase in backpressure. However the velocity is more important than some backpressure up to a point so going with huge pipes is not a good thing all the time.

Anyway those pipes are just WAY too big. If anyone is going for a true dual than you better make sure you are running SMALLER pipes than the OEM single pipe if you want any chance of not losing hp. Put true duals with large diameter piping and you are killing hp in the low-mid range and probably even upper end since 220hp does not pump out enough gas to flow in those size of pipes.

[Route 16]

Those are Detail Addict exhaust pipes. Would backpressure be no problem if the muffler was still on? With those pipes I'll be installing my Eisenmann race muffler. My current set up now is pretty decent, I'll be dynoing both set ups in Feb.

Disregarding performance since in actually I may never track and if I do for that day, it'll be so random and once in a lifetime with that car. Basically I just want the sound (which will definitely be there) but I want no loss to my daily driving pleasure. I don't WOT very often, I just do it to scare sleepy drivers.

Originally Posted by DylanMckay

I do not know who's exhaust this is but those pipes are WAY too big. Every response on here is missing the only thing that actually matters which is exhaust velocity!

You want the absolutely most free flowing exhaust you can get with no backpressure BUT you need to maintain or improve the velocity of the gases to not lose power and perhaps gain a hp or two.

The larger diameter pipes with a 3.0 220hp engine does not produce enough gases to run at a high velocity which is why the OEM pipes are much smaller diameter which keeps the velocity and scavenging going properly. So many people mistakely call this "needing backpressure" when it is actually needing velocity which sometimes inevitibly causes some increase in backpressure. However the velocity is more important than some backpressure up to a point so going with huge pipes is not a good thing all the time.

Anyway those pipes are just WAY too big. If anyone is going for a true dual than you better make sure you are running SMALLER pipes than the OEM single pipe if you want any chance of not losing hp. Put true duals with large diameter piping and you are killing hp in the low-mid range and probably even upper end since 220hp does not pump out enough gas to flow in those size of pipes.

[DylanMckay]

Originally Posted by yoko kai

Those are Detail Addict exhaust pipes. Would backpressure be no problem if the muffler was still on? With those pipes I'll be installing my Eisenmann race muffler. My current set up now is pretty decent, I'll be dynoing both set ups in Feb.

Disregarding performance since in actually I may never track and if I do for that day, it'll be so random and once in a lifetime with that car. Basically I just want the sound (which will definitely be there) but I want no loss to my daily driving pleasure. I don't WOT very often, I just do it to scare sleepy drivers.

Hmm seems like you missed the entire point and message I was trying to convey. The pipes are way WAY to big in diameter therefore the exhaust gases will be flowin gMUCH too slowly and scavenging effects will be gone and power will be lost at low and mid end which this car already really lacks.

Putting a source of back pressure anywhere does not help-the least possible backpressure is ALWAYS the best. A restrictive muffler (although eisenmann is probably pretty free flowing) is not helping a problem with pipes being too large.

As long as you are ok with LOSING power especially on the bottom-middle end than you are fine-but if expecting some power this will not do it and will lose it

[Route 16]

Ahh now I see, this month I'll be trying the prototype on my car for a couple of days. By then I can actually test out what you really mean.

Originally Posted by DylanMckay

Hmm seems like you missed the entire point and message I was trying to convey. The pipes are way WAY to big in diameter therefore the exhaust gases will be flowin gMUCH too slowly and scavenging effects will be gone and power will be lost at low and mid end which this car already really lacks.

Putting a source of back pressure anywhere does not help-the least possible backpressure is ALWAYS the best. A restrictive muffler (although eisenmann is probably pretty free flowing) is not helping a problem with pipes being too large.

As long as you are ok with LOSING power especially on the bottom-middle end than you are fine-but if expecting some power this will not do it and will lose it

[DylanMckay]

If you have the chance to build your own exhaust-the absolute best thing you can do is keep the overal diameter of the piping the same but remove the points of restriction including 1. Primary cats 2. The rear muffler.

The resonators provide no resistance or backpressure so no benefit at removing them. Secondary cats very little resistance.

The problem with many afermarket exhausts is while they get rid of a restrictive point such as the rear muffler, they negate any potential slight gain by increasing pipe size.

Increasing pipe size can yield you a few hp increase at the very top of the rev range at a pretty useless point in the powerband. However for advertising this allows them to claim xyz hp increase.

The OEM pipe size is always a compromise as lower and middle rpms produce less exhaust and the pipes need to be smaller to keep the velocity flow up to scavenge properly (creates a suction effect by moving quickly thuse sucking in the air/fuel of the next charge cycle-scavenging).

However the pipes are usually a compromise and thus for the very highest rpms the pipes are a bit too small to be ideal. However especially this type of engine that already lacks low-mid torque and really relies on top end high rpm power, it is worth the compromise to maintain something in the middle of the curve at the expense of a couple top end hp that you probably would never notice.

Bottom line-remove primarys and rear muffler restrictions. Do not mess with OEM diameter piping or shape and you have the absolute best flowing exhaust possible on that car. You will lose power going to a true dual on this car. Not nearly enough exhaust flow to effectively use two completely seperate pipes. The total surface area of the pipes if you use 2 the whole way back will be much bigger than the 1 OEM pipe (Unless you use two really tiny pipes which is tough to do) That means exhaust gas just gets sluggish once it seperates into two paths and creats no vaccuum which means no scavenging which means no power-and loss of power

[SR2007]

Originally Posted by DylanMckay

If you have the chance to build your own exhaust-the absolute best thing you can do is keep the overal diameter of the piping the same but remove the points of restriction including 1. Primary cats 2. The rear muffler.

The resonators provide no resistance or backpressure so no benefit at removing them. Secondary cats very little resistance.

The problem with many afermarket exhausts is while they get rid of a restrictive point such as the rear muffler, they negate any potential slight gain by increasing pipe size.

Increasing pipe size can yield you a few hp increase at the very top of the rev range at a pretty useless point in the powerband. However for advertising this allows them to claim xyz hp increase.

The OEM pipe size is always a compromise as lower and middle rpms produce less exhaust and the pipes need to be smaller to keep the velocity flow up to scavenge properly (creates a suction effect by moving quickly thuse sucking in the air/fuel of the next charge cycle-scavenging).

However the pipes are usually a compromise and thus for the very highest rpms the pipes are a bit too small to be ideal. However especially this type of engine that already lacks low-mid torque and really relies on top end high rpm power, it is worth the compromise to maintain something in the middle of the curve at the expense of a couple top end hp that you probably would never notice.

Bottom line-remove primarys and rear muffler restrictions. Do not mess with OEM diameter piping or shape and you have the absolute best flowing exhaust possible on that car. You will lose power going to a true dual on this car. Not nearly enough exhaust flow to effectively use two completely seperate pipes. The total surface area of the pipes if you use 2 the whole way back will be much bigger than the 1 OEM pipe (Unless you use two really tiny pipes which is tough to do) That means exhaust gas just gets sluggish once it seperates into two paths and creats no vaccuum which means no scavenging which means no power-and loss of power

WOW, great write up with information. Def clears a lot of rumors and misinformation out of this thread. It goes back to the other articles I've read on back pressure and airflow, just not clicked reading your message several times. lol Saying all that, I'll stick with the stock diameter tubing untill I can make up the difference in HP down line. So far my intentions are running the MMW headers and nothing else for now. See how that goes. Secondary plan is to run a incorporate the first cat back in there via custom setup just to assist in balancing out the airflow. I have no intention of ever putting the rest back in, simply for weight purposes and obivisouley it suites no real purpose. I'll have to nix the idea of going true dual based upon your information. Ill end up keeping the stock pipe set-up from the headers into a solid tube back into a Y-split about mid way to accomplish the rear quad-setup. I intend on down the line purchasing the MMW SC kit this summer once its been tested around and then reconsider increasing pipe size at that point. The kit should put me around the 335i range, saying that Im assuming that their pipes are bigger in diameter..... So increasing to their range shouldn't be an issue going off the hp ratio to exhaust diameter. At the moment gaining any real power is not a goal, getting that nice aggressive eurosound is tho. Ill worry about the HP when I start tearing apart the motor this summer for a 330 head swap and SC kit.