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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > NA Engine (non-turbo) / Drivetrain / Exhaust Modifications > Catless Headers ?



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      12-07-2012, 09:10 PM   #1
Amini77
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Catless Headers ?

So I was at the mechanic today doing some service and the owner, also a friend of mine, of course he's into cars and such he owns a e36 m3 track car and a 69 camaro ss. I was telling him I want to get catless headers for my 330xi and he was telling me it probably isn't a good idea because I would lose low end torque and get bad mpg. He also said a buddy of his who did this, his car was actually feeling a lot slower on the street. So I figured maybe its the placebo effect where just because it sounds louder, the guys on the forum think its faster. He also mentioned the Check Engine Light popping up, but I hear that's fixable with a BMS Downpipe Fix, right?

Specifically I want MMW ones, it doesn't make a difference which ones but is this true? I was also thinking of doing a 2ndary cat delete but I'm starting to change my mind after hearing this. On top of either the headers or 2ndary cats I wanted to throw an AA Tune on. What do you guys think?

A friend was telling me that the drone is going to be stupid loud so I figure if I get maybe a Vibrant Resonator will that tone it down a bit? Tell me what you guys suggest I also want to do quads if it makes a difference so help me out guys, THANKS!
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      12-07-2012, 10:13 PM   #2
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- theres really no way to tell how bad if any exhaust drone with a setup thats not done yet
- the BMS downpipe fix should eliminate a CEL
- you shouldnt lose low end torque because theres still restriction in the rest of the exhaust system

sounds like he doesnt know what hes talking about
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      12-07-2012, 10:33 PM   #3
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I get better gas mileage.
I have zero done with my exhaust. (You've seen the video, you cant hear it unless you're foot is in it)
There is no noticeable loss of power or torque down low. There is a gain in mid to high RPM.
I'll be doing a dyno soon.
Finally, I don't think you'll find any MMW headers left. He had one set left and if they are gone he probably wont be making any more. Would be best to check his facebook page.
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      12-08-2012, 12:21 AM   #4
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Quote:
Originally Posted by 1slowbmw View Post
- theres really no way to tell how bad if any exhaust drone with a setup thats not done yet
- the BMS downpipe fix should eliminate a CEL
- you shouldnt lose low end torque because theres still restriction in the rest of the exhaust system

sounds like he doesnt know what hes talking about
Where would the rest of the restriction be with both cats gone? The resonator and muffler?
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      12-08-2012, 12:23 AM   #5
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Quote:
Originally Posted by Johnny D View Post
I get better gas mileage.
I have zero done with my exhaust. (You've seen the video, you cant hear it unless you're foot is in it)
There is no noticeable loss of power or torque down low. There is a gain in mid to high RPM.
I'll be doing a dyno soon.
Finally, I don't think you'll find any MMW headers left. He had one set left and if they are gone he probably wont be making any more. Would be best to check his facebook page.
I really hope he will make more, been planning this for months. They're the only headers that fit without trimming anything out right?
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      12-08-2012, 12:59 AM   #6
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I had custom catless headers done and I have dyno'd. Most of what you were told is simply false. Check my thread for evidence. There was zero increase in sound at all with my design. There were gains of HP and torque all throughout the curve. TQ gains were greater than HP. My MPG has improved noticeably. At times it was up by 20%. Greatest gains were from 2.5k to 3.5k RPM.

http://www.e90post.com/forums/showthread.php?t=772142
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      12-08-2012, 01:01 AM   #7
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Quote:
Originally Posted by mapleridge View Post
I had custom catless headers done and I have dyno'd. Most of what you were told is simply false. Check my thread for evidence. There was zero increase in sound at all with my design. There were gains of HP and torque all throughout the curve. TQ gains were greater than HP. My MPG has improved noticeably. At times it was up by 20%. Greatest gains were from 2.5k to 3.5k RPM.

http://www.e90post.com/forums/showthread.php?t=772142
Where did you get these done? Pretty simple design right? You think reputable muffler shop can do it?
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      12-08-2012, 01:05 AM   #8
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Quote:
Originally Posted by Amini77 View Post
Where did you get these done? Pretty simple design right? You think reputable muffler shop can do it?
For me it was multi stage deal whereby I had collectors cast, then I had a jig built and then fabricated. They are totally new, It's not just an oem manifold that has had the cats cut. I am working to get a set made with mandrel bends instead of welding and going from there. A few people said they would like a set.
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      12-08-2012, 01:36 AM   #9
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Quote:
Originally Posted by mapleridge View Post
For me it was multi stage deal whereby I had collectors cast, then I had a jig built and then fabricated. They are totally new, It's not just an oem manifold that has had the cats cut. I am working to get a set made with mandrel bends instead of welding and going from there. A few people said they would like a set.
I'd be down if MMW stops making them
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      12-08-2012, 02:03 AM   #10
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Quote:
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I'd be down if MMW stops making them
Yeah. They are two different beasts. The MMW would be louder and they are not a direct bolt on option. Mine bolt up to your stock exhuast. Mine are good if you want extra power but to keep whatever exhaust note you have or lack thereof. Plus, his are ceramic. These are stainless. I haven't seen any dyno charts from his either, but I would imagine the gains would be quite similar. In the end, same purpose but different offerings.
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      12-08-2012, 03:46 AM   #11
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Quote:
Originally Posted by mapleridge View Post
Yeah. They are two different beasts. The MMW would be louder and they are not a direct bolt on option. Mine bolt up to your stock exhuast. Mine are good if you want extra power but to keep whatever exhaust note you have or lack thereof. Plus, his are ceramic. These are stainless. I haven't seen any dyno charts from his either, but I would imagine the gains would be quite similar. In the end, same purpose but different offerings.
I see, but what difference would it make if its ceramic vs stainless? I thought MMW headers were bolt on you sure about that?
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      12-08-2012, 10:06 AM   #12
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Quote:
Originally Posted by Amini77 View Post
I see, but what differerence would it make if its ceramic vs s. inless? I thought MMW headers were bolt on you sure about that?
They don't have lower flanges from the pics I saw. Johnny d I believe welded his flange on. It may be like a clamp but that would require cutting flanges on the mid pipe. You would have to inquire further from someone who owns a set but there is no lower flange preattached.

Ceramic is usually applied over a mild steel that is prone to rusting when unprotected. Ceramic is supposed to keep heat in the pipes which is good for the engine. The metal needs to be at least 16 gauge or else depending on the coating the heat could cause cracking. His are probably that thick but I never saw anything official. It also should create resistance to corrosion but I couldn't tell if the inside was coated as well or not.

Stainless steel in and of itself is corrosion ressistant.
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      12-08-2012, 12:34 PM   #13
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Quote:
Originally Posted by mapleridge View Post
They don't have lower flanges from the pics I saw. Johnny d I believe welded his flange on. It may be like a clamp but that would require cutting flanges on the mid pipe. You would have to inquire further from someone who owns a set but there is no lower flange preattached.

Ceramic is usually applied over a mild steel that is prone to rusting when unprotected. Ceramic is supposed to keep heat in the pipes which is good for the engine. The metal needs to be at least 16 gauge or else depending on the coating the heat could cause cracking. His are probably that thick but I never saw anything official. It also should create resistance to corrosion but I couldn't tell if the inside was coated as well or not.

Stainless steel in and of itself is corrosion ressistant.
I'll definitely be keeping an eye on you if you go through with making a few
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      12-08-2012, 03:47 PM   #14
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Quote:
Originally Posted by Johnny D View Post
I get better gas mileage.
I have zero done with my exhaust. (You've seen the video, you cant hear it unless you're foot is in it)
There is no noticeable loss of power or torque down low. There is a gain in mid to high RPM.
I'll be doing a dyno soon.
Finally, I don't think you'll find any MMW headers left. He had one set left and if they are gone he probably wont be making any more. Would be best to check his facebook page.
i cut my cats out and muffler and left the res and 2ndaries. i get way betteer gass millage and theres a tiny but from like 500-2k but after that mine pulls hard as fuck
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      12-08-2012, 06:15 PM   #15
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Quote:
Originally Posted by Amini77 View Post
Where would the rest of the restriction be with both cats gone? The resonator and muffler?
Just the length of pipe should be enough restriction to not lose low end torque
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      12-09-2012, 12:46 AM   #16
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Quote:
Originally Posted by 1slowbmw View Post
Just the length of pipe should be enough restriction to not lose low end torque
Thanks for the info
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      12-28-2013, 08:39 PM   #17
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dont they check for smog in CA? I might be moving there and I have catless headers. I do have the tune to get rid of the emissions light but dont they check for smog by some sort of sniffer device? I still have my secondaries
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      12-28-2013, 09:03 PM   #18
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Quote:
Originally Posted by Tim603 View Post
dont they check for smog in CA? I might be moving there and I have catless headers. I do have the tune to get rid of the emissions light but dont they check for smog by some sort of sniffer device? I still have my secondaries
This was a year ago I had little knowledge about all this, they do check smog here but I hear they're changing it to an OBD test for cars 2000+. I think they're currently still doing the sniffer though.
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      12-31-2013, 06:03 PM   #19
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Quote:
Originally Posted by Amini77 View Post
This was a year ago I had little knowledge about all this, they do check smog here but I hear they're changing it to an OBD test for cars 2000+. I think they're currently still doing the sniffer though.
gotcha I know I just found this thread on google lol but alright well that would be nice if they just switched to an OBD test. I would hate to have to put cats back in
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      01-03-2014, 09:27 PM   #20
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I definitely gained power across the band, saw maybe 1mpg better milage, and have no CEL thanks to my tune turning down(not off) the sensors.
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