[Eric@AMS]

Most of you have been following our thread on building an exhaust for the 335i HERE. As many of you know the BMW 335 uses a true dual exhaust system, meaning an exhaust pipe is dedicated for each turbo. The stock turbos are very small…the smallest we have seen and we deal with turbos all day long. Most aftermarket companies run 2 -2.5” piping for their exhaust and we came at this from a different perspective. From our experience a single 3” exhaust flows up to 600whp without any significant restriction. We’ve tested this on our EVO’s by dropping the exhaust after the downpipe. As you can see a 3” exhaust pipe can carry some serious power.

But why 3” you ask? Well by going with a single 3” pipe under the car it will not only help lower the cost of us making a true dual 2.5” system but it will also and more importantly make it lighter weight less weight can only mean a better hp to weight ratio and thus make your car faster in the process. It’s win win.

Another big advantage to going with one 3” pipe is the future fitment of this piece. Most N54 owners will not be upgrading turbos in the future but some will. We have some preliminary plans of building a larger single turbo kit. In doing a single kit a twin 2.5” system will just allow for an unnecessary “Y” junction after the turbo. So our goal was not only to make a system that flows as well as a dual 2.5” but also is modular to work with a kit we plan to make down the road.

For testing we also built a downpipe for the car. The downpipe consisted of 2 -2.5” pipes joining in a nice "Y" transition to one 3” connection that hooked up to our 3” cat-back exhaust.

The Test car:

2007 BMW 335i 6MT
Modifications: Burger Motorsports Juice Box 3 (JB3)
Everything else stock

The two systems being tested:

AMS System: 3” downpipe and catback exhaust system with High flow cat and Resonator

Twin 2.5” System: Autobahn Exotics catless true divorced 2.5” dual exhaust system with Riss Racing Catless Coated Downpipes.

Dyno: Dynojet 424X

I want to note that although our system does have a high flow cat inline we use a very high quality steel core cat. In past tests on 350whp cars we have seen virtually zero difference in HP between this particular high flow cat and no cats at all. Spool might be slightly affected but it will be negligible. True the 335i might be different but at these boost levels we think that is unlikely. So all things considered we take this as a fairly even playing field. We will try a system with no cat but we really wanted to test what the average consumer would want and I don’t think anyone wants a service engine soon light

One of the things we wanted to really take into account when performing this test was to record accurate gains from each system. Some of the claims by manufactures of various Downpipes and catbacks have been pretty outlandish. One thing you will learn quickly about AMS is when we post or advertise a gain…you can bet that is a true statement and easily duplicated by the end user. We went into this test expecting about 15 whp gain from a full exhaust system on the 335i.

So here it is. The two exhaust systems compared right on top of each other. It’s scary how close they are. Spool seems to be a hair better with the AE Riss Racing combo but maybe that is to be attributed to the presence of the HFC in the AMS system. Further testing will have to answer that question.




As you can see from the graph above there isn’t much to be gained from a true dual 2.5” system compared to a single 3” system. The red line represents the AE/Riss Racing system and the Green represents the AMS system.

Now that we have the comparison out of the way I wanted to show REAL WORLD gains from a turbo back exhaust on this car. We have seen some pretty big gains advertised from just adding downpipes to the 335i and we were a bit skeptical about it. So the below graph is comparing our completely stock 335i to the same car with our full prototype downpipe/catback combo. As you can see the gains were about what we had estimated 15whp and just over 20 ft lbs of torque.

The blue line represents the stock car with an AMS full exhaust including AMS downpipes

The Pink line represents the same care completely stock.




In conclusion our initial thoughts were proved and a single 3” system that splits to two tips can support power just as well as a true 2.5” system.

Some things to take away from this test:

First the AE (Autobahn Exotics) catback is a pretty nice system. We had no plans on making a dual 2.5” system but based on this test and its fitment we do plan on carrying it for customers that feel they must have a completely divorced system.

The Riss racing downpipes however did not fit very well. It took almost twice as long to install these pipes compared to the ones that we designed to bolt up to our system and once installed the flanges that were supposed to be flush were not. This caused the catback to not bolt up evenly and in the end caused the tips to sit slightly off in the bumper. There was no adjustment that could fix this. Also the downpipes made contact with a few points on the car that could not be avoided no matter what level of adjustment were made. We did purchase these pipes second hand so maybe heat from the previous owner had tweaked them a bit but our set fit very poorly. Another problem was the obvious presence of a Service engine soon light on the dash with the absence of any catalytic converter. I am sure that adding a pair of cats to the system would eliminate that problem but unless they are using extremely well made and high performing cats like we are using we suspect it would affect Hp/Tq and spool. We have not conducted this test though so we cannot say for certain.

Are we disappointed that full downpipe/catback exhaust systems only make about 15whp and 20ft lbs of torque over stock. Absolutely not, that is about what a turbo back system on this car should make. BMW did a pretty good job from the factory and left little on the table. It should open your eyes though to really look into what some companies claim for gains on their products. We have always adopted a no nonsense approach to how we advertise our product and I hope this test will be a shining example to that. This was a pretty black and white test and the dyno doesn’t lie.

Should those of you that currently have a AE/RR combo sell your system…we are not saying that at all. I think in fact the above graph shows the opposite. We are merely trying to bring something new to the table. A lightweight and sound tunable system that can support great amounts of power and has the ability to bolt up to a turbo system to be made by us in the future.

I will say that this prototype system is just that...a prototype. We have to clean it up and have pipes bent and what not if we are to make this a production kit. We have also not completely decided on what muffler we would like. Also Tip's of course will have to be added and that's a pretty debatable topic so we are going to have to spend some time looking into tip selection. Realistically we will not be able to sell a system until sometime mid to late spring but who wants to put an exhaust on in the winter anyways

Thanks for taking the time to read. I will make sure we continue to post up tests like this to help keep everyone up to date on AMS’ continued development of the N54 engine platform.

Thank you,

Eric Gaudi
Sales Manager
AMS Performance

[scollins]

Very cool! How much does your exhaust weigh, from the downpipe back? And, how do you manage the connection to the stock DPs?

I've got the AE system right now, and it dumped around 23 lbs off the car. I haven't done DPs yet, but if/when I do, they will most certainly be with HFCs.

Great work guys!

[LOLrance]

You guys are one of the best in the business. Anxiously waiting for your exhaust to come out.

[Eric@AMS]

Originally Posted by scollins

Very cool! How much does your exhaust weigh, from the downpipe back? And, how do you manage the connection to the stock DPs?

I've got the AE system right now, and it dumped around 23 lbs off the car. I haven't done DPs yet, but if/when I do, they will most certainly be with HFCs.

Great work guys!

As it sits right now our catback even with a HFC and Resonator built into it would weight 35 pounds less than the stock unit We would have to build a small transition pipe to bolt to the stock downpipes. We are moreso building this system to be sold as a FULL turbo back system with the downpipes incorporated. We have to see how beneficial it would be to make this system to be able to bolt up to the stock downpipes. hopefully though we can get this full downpipe and catback system priced cheaper then most companies catback alone.

Just to give you an idea the full factory exhaust including downpipes weights in at 95 pounds

The Full AMS system with a resonator and a cat only weighs in at 52 pounds!!!! that's a 43 pound weight savings!

Plus this system is just a prototype and if we were to actually produce it the overall weight should get even lighter.

Eric

[Sal@AUTOcouture]

Originally Posted by l4wr3nc3

You guys are one of the best in the business. Anxiously waiting for your exhaust to come out.

[Nebster]

watching, i'll be over the weekend after you release it.

[Turkishexpress]

Thats why I have refrained from getting any other exhaust

Also, were these results possible with the JB3 or the stock ecu? I know you said the car had JB3 on it but expected a bit more power for a full tbe

[XPO186]

Cool... I really like how you guys kept a single turbo upgrade in mind for the current design. And this seems to be the only exhaust specifically marketed as a complete turbo-back setup... Nice!


I can't wait to see what other products you guys will come out with...

[NM_BMW]

I'm guessing the gains that you noted on both systems were with a stock ECU. The real gains from these bolts ons come from a tune.

Anyways, I can't wait to see what else AMS is to offer. I'm waiting to see what you guys come up with for a FMIC.

[RiXst3r]

Awesome work Eric! I love the honesty that your company offers to its customers...

Keep up the good work!

-Rick

[AV9]

looking forward to hearing more news!

[JB335]

Thanks for all of your hard work, AMS. I look forward to being one of your clients in the future.

[Fraggy]

Has no one asked how it sounds?

[jpsimon]

Originally Posted by Fraggy

Has no one asked how it sounds?

many people have asked how it sounds in the original thread

[Eric@AMS]

Thank you again everyone for all the nice comments.


To answer a couple of questiones:

the first graph is from the exhaust along with a JB3

The second graph is the gains from our exhaust from stock.

We have a just JB3 tune graph that I will overlay with the first posted graph to give you an idea of what a turbo back can gain with an JB3 behind it. It will be a little bit higher but not that much.

Eric

[Eric@AMS]

We have a video posted of the sound on streetfire:

This is just as the system was tested, HFC, Resonator and on the loudest sound adjustment setting offered.

http://videos.streetfire.net/video/A...est_201897.htm

[brusso]

Just one request...... please do some testing and get rid of the drone that we auto guys experience with the dual exhaust set ups. I kept my catless dps and got rid of the exhaust just for that reason. I also couldn't stand the vibration it created in the car as well.

Damn drone...... I would love your single exhaust with no drone ! for the auto .

[Adamk24]

I traded in my Evo with a bunch of AMS goodies on it for my 335 about 2 months ago, so I cannot express how excited I am to see you guys getting involved in the scene. Single turbo conversion? Yes please! Single pipe exhaust? A downpipe feeding into a single exhaust with 1 high flow cat sounds cheap and effective. I would definitely be interested!

Quick question, when you said "by going with a single 3” pipe under the car it will not only help lower the cost of us making a true dual 2.5” system " did you mean it will be lower than the cost of making a true dual 2.5" system?

Keep on plugging away guys, look forward to being a future customer

[Eric@AMS]

Thanks again guys. I meant that it will be cheaper then Making a 2.5" system all together. We have no plans on making a dual 2.5" system but I think we will be carrying the AE system. I have been driving a few days around on it now and its a pretty nice system.

I personally prefer the sound and resonance of ours but that's why we will offer a choice to our customers.

Eric

[Fraggy]

Originally Posted by jpsimon

many people have asked how it sounds in the original thread

Didnt realize there was an original thread, my apologies.

[jpsimon]

Originally Posted by Fraggy

Didnt realize there was an original thread, my apologies.

The very first sentence in this thread points you to that thread

[BaLLzZz]

Very nice work I also love the tone of the AMS. Cannot wait until some real products start coming out. I might have to buy another 335i!