[fl335i]

Hey guys, first post on this board. I've had my '07 335i for about 2 months now, already did the Golf Tee Mod (unplugged the one exhaust flapper). But I'm looking for a cat-back. Seems like there are a lot of brands and they all seem to gain about 10hp/10 #/Ft at the wheels. What seems to be a good cat-back or the one with the most power? I'm seriously looking at the AMS b/c it's a single 3" and has a sideways dual outlet muffler like the LS1 F bodys. Does anyone have experience with this exhaust? Recommendations?

[fl335i]

so nobody has been doing cat-backs???

[Amir87]

Pick a catback for sound and not performance, since most catbacks will yield around te same whp. As for the AMS, seems like a good exhaust and only full 3inch single pipeing exhaust out there.

[BrianMN]

Hi and welcome!

Many people here are running catbacks. Most of it is personal preference of how each sounds. Unfortunately, videos' don't help too much. It's best to go to a meet and hear them in person.

As for the AMS exhaust,, I have it with catless downpipes and it's my favorite I've heard. AE is also amazing, as well as many of the 'quality' brands..(NOT ebay pipes). What I like about AMS is that it cuts down a bit of weight, but even a fully divorced setup will cut some weight from stock system.

Happy motoring!

[scottp999]

Autobahn Exotics, Vanguard, and HKS are 3 that you can't go wrong with.

[Forcefed3]

Originally Posted by scottp999

Autobahn Exotics, Vanguard, and HKS are 3 that you can't go wrong with.

I agree, except I dont like the HKS personally. I'd say go with Vanguard.

[fl335i]

so Vanguard or AMS. Leaning toward AMS single 3" system. I will try and listen to them in person when I'm ready to buy a system. But first onto more important things.... LSD. Thanks guys.


One side note/Q. Do any of these cat-backs have a CARB approvals? 50 state legal approvals. I'd like to keep my car as legal as possible and like to have literature/approvals for things like exhaust b/c I've already been down this road in the state of FL even though we have no emissions testing or safety checks what so ever. Cops will pull you over and tell you your muffler is illegal b/c it's aftermarket and then it's on you to prove them wrong. I used to keep a copy of the FL state law in my glove box along with a copy of the CARB approal # and Literature. Fl did pass some tuff laws in the early mid 2000's to curb the buzz box fast'n curious effect. What the law basically states is the muffler or exhaust in general need to meet OEM spec or you will be subject to a Decibal test by your local law agency which is done at 50' away IIRC at varying speeds/throttle. So when my wife and I got pulled over in our '91 MK3 Turbo Supra and they found a 5' asian girl driving.. probly not what they expected. Not to mention I had literature in the glove box for the Cat-back system. They probly expected some ricers with cluelessness. Needless to say after 3 cop cars pulled us over for almost 1hr they let us go scott free.... Bottom line is CARB approval and 50 state legal approval is a big deal for me.

[scottp999]

If those are truly big concerns, then I think you should leave the stock exhaust on or just get the muffler replacement with the BMW performance exhaust or dinan exhaust.

You could also ask magnaflow if their exhaust has the approvals, but when you put on a catback (i call it a downpipe back on this car), most systems remove the secondary cats, which is not legal at the Federal level. In adiditon, even the ones that offer secondary cats are illegal at the federal level because almost all do not meet the EPA requirements for replacing the cats with something different. Read this at magnaflows web site:

http://www.magnaflow.com/02catalytic...sics/04epa.asp

[fl335i]

what. on my supra I got a Tanabe and it had the approval.... leave it to bimmer to make some complex system.

[Ghines1279]

hey bro, Take advantage of Florida's lax emission laws. STRAIGHT PIPES! I couldnt pass California emissions to save my life with my old bustang 5.0. Florida is awesome.

[Bullet]

I got Vangaurd seriously in love with it.. such a huge improvement from stock!!

[fl335i]

Seriously probly going tha AMS route. I like the single 3" design. 3.0L I-6 Turbo only needs a single 3" pipe until you get to like 600+HP. Vanguard is currently in 2nd place.

[Nutballa]

Originally Posted by fl335i

Seriously probly going tha AMS route. I like the single 3" design. 3.0L I-6 Turbo only needs a single 3" pipe until you get to like 600+HP. Vanguard is currently in 2nd place.

You should reconsider...This is my Vanguard exhaust video. Note: it sounds deeper in person.

[TwinTurboXI]

I think the BMW performance exhaust system and the Dinan exhausts are CARB approved... might be worth looking into.

[myown335xi]

Loving the video, sounds great. Just persuaded me.

[fl335i]

Moses that sounds good. Just need to hear each in person for the hair splitting decision.

[scottp999]

Dual 2.5" = 5"
vs
Single 3"

I'd take 5", plus you are not mixing pulses from both banks into one pipe. The more free flowing the better.

[cn555ic]

Originally Posted by Nutballa

You should reconsider...This is my Vanguard exhaust video. Note: it sounds deeper in person.

I heard the exhaust in person and its nice but its really has a deep throaty exhaust thats for sure, with DPs its alot louder than other exhausts..

[fl335i]

Guys. I did some quick math and research. First off I come from the turbo supra world, so a single exhaust is peformance. But after refreshing my mind, the piping diamter for the 3.0L I-6cyl Turbo supras I was used to are 90mm, or 3.5". Not 3" as I was thinking.

The square area of piping options, ranging from smallest to largest.

Single 3": 7.068

Dual 2.25":7.952

Single 3.5": 9.62

Dual 2.5": 9.817

Next, I believe our cars have dual 2.5" or 2.25" outlet flanges at the downpipes? Personally I'd like a single 90mm (3.5") system but it doesn't exist. I think the single 3" is deffinately an improvment over stock. It's also the lightest weight system. It will probably give you the best overall torque curve too. However, the question remains how much HP is your goal; how fast do you want to go. I think a dual 2.5" system is the way to go with our cars if you want big HP #'s especially being it's already dual from the factory. One concern I have with a lot of aftermarket exhausts is the lack of "cross-over" pipes. or X, H whatever pipes to help balance things out. I think the stock system even has one on the rear.

I just have to ask myself, am I going to mod my 335i to have more than approx 350-ish HP. For most guys, that's going to be a "NO". So unless you're going for big numbers the single 3" will be the most benneficial for street use. Light weight, high velocity gases which give you a decent torque curve.

By design I really like the Magnaflow Touring sytem. It's dual, and they put a nice X pipe in there and a single sideways muffler and have all 2.5" mandrel piping. This might be better suited for bigger HP #'s.

The search continues...

EDIT: Just looked at Autowerke's exhaust. They actually have a "channel pipe" which is supposed to be even better than a H or X. It's the 3rd generation crossover pipe supposedly. I really am impressed with the autowerke's.... I'm pretty sure this is the route I will be going. It looks like they put a lot of engineering into it and not just looks. I don't see anyone else incorporating a "channel pipe" in their duals. The next best might be the Magnaflow with the X pipe and dual 2.5" pipe. Autowerke's is claiming some huge dyno gains though... 15+hp and all. Not sure about that, but by design it looks very promising. They are on top of my list. 2nd is AMS or Magnaflow.

[scottp999]

Many people believe an X pipe or any exchange between pipes is not good on a turbo car and that fully divorced is better (for twin turbo).

This is a great thread on that debate: http://www.e90post.com/forums/showthread.php?t=70267

[Penn999]

Originally Posted by fl335i

Guys. I did some quick math and research. First off I come from the turbo supra world, so a single exhaust is peformance. But after refreshing my mind, the piping diamter for the 3.0L I-6cyl Turbo supras I was used to are 90mm, or 3.5". Not 3" as I was thinking.

The square area of piping options, ranging from smallest to largest.

Single 3": 7.068

Dual 2.25":7.952

Single 3.5": 9.62

Dual 2.5": 9.817

Next, I believe our cars have dual 2.5" or 2.25" outlet flanges at the downpipes? Personally I'd like a single 90mm (3.5") system but it doesn't exist. I think the single 3" is deffinately an improvment over stock. It's also the lightest weight system. It will probably give you the best overall torque curve too. However, the question remains how much HP is your goal; how fast do you want to go. I think a dual 2.5" system is the way to go with our cars if you want big HP #'s especially being it's already dual from the factory. One concern I have with a lot of aftermarket exhausts is the lack of "cross-over" pipes. or X, H whatever pipes to help balance things out. I think the stock system even has one on the rear.

I just have to ask myself, am I going to mod my 335i to have more than approx 350-ish HP. For most guys, that's going to be a "NO". So unless you're going for big numbers the single 3" will be the most benneficial for street use. Light weight, high velocity gases which give you a decent torque curve.

By design I really like the Magnaflow Touring sytem. It's dual, and they put a nice X pipe in there and a single sideways muffler and have all 2.5" mandrel piping. This might be better suited for bigger HP #'s.

The search continues...

EDIT: Just looked at Autowerke's exhaust. They actually have a "channel pipe" which is supposed to be even better than a H or X. It's the 3rd generation crossover pipe supposedly. I really am impressed with the autowerke's.... I'm pretty sure this is the route I will be going. It looks like they put a lot of engineering into it and not just looks. I don't see anyone else incorporating a "channel pipe" in their duals. The next best might be the Magnaflow with the X pipe and dual 2.5" pipe. Autowerke's is claiming some huge dyno gains though... 15+hp and all. Not sure about that, but by design it looks very promising. They are on top of my list. 2nd is AMS or Magnaflow.

I am currently running the active autowerke exhaust and I love it, the exhaust note is manageable and I do plan on cracking 400whp so thats the route that I went. The only way I would ever get rid of this is if HPF offers their muffler-less exhaust at a decent price. Knowing HPF it will most likely be over $2k. I have not dynoed my car yet but I plan on doing it here in the next couple weeks. I can post some videos if anyone is interested. Also I will take a couple of videos with and without the cats since I am fitting my ar downpipes on next week. Its loud already and Im sure I am going to need some resonators after I go fully catless. I already get told, "I heard you a couple blocks away before you got here...."

[fl335i]

wow. Good read man. Didn't know that about the whole scavenging effect doest not hold valid after the turbo, but it makes sense. so for our cars a single 3.5" or a dual 2.5" system will be optimal for stock to 500HP. I went back and looked at vanguard and autowerke's. Autowerke is claming scavaging with their X pipe and looks like vanguard has a H pipe? Can't really tell.


I stand corrected. I love learning.