[Sal Collaziano]

This place is freakin' awesome. I've been here a few weeks and have learned so much. Already purchased a JB+ with BT cable (received in less than 24 hours), M-Tech trunk spoiler, blackline tail lights and two new sensors after breaking "the clip" while installing the JB+.. I purchased a JB3 with Dual Cone Intake just a few minutes ago (kinda surprised it's not here already, actually)...

Next up is exhaust.. I don't want to go voiding my warranty so I know I have to remove the intake and JB3 when I go in for service. I'm still learning about aftermarket exhausts - so I may be lost here - but if I'm installing downpipes and a cat back exhaust, do I lose ALL my catalytic converters? Or just the secondaries and/or anything else? I really don't care too much about voiding my "exhaust" warranty because #1: I've never had an exhaust warranty repair - and -#2: If I do, I'll just pay for it out of pocket. Really - how much could it cost?

Any input and/or advice would be greatly appreciated.

Thanks in advance!

[Express]

I'll go out on a limb here and guess.

It's not your exhaust warranty, it's that you have a turbo car and it needs some backpressure. When you have a larger exhaust in diameter, you lose some pressure and you can cause problems with other components in the motor.

Correct me if I'm wrong.

[Sal Collaziano]

I was under the impression that a car with turbo needs less back pressure than a naturally aspirated car... So I thought you'd want to remove as much back pressure as possible...

[D.B.S]

http://www.e90post.com/forums/showth...6974&highlight

This is a good read when it comes to DP's and the such, Mr. 5 doing an outstanding job... Bigger is Better, but TOO big and you start to loose out on some power... Do some research, and you'll find what is good for you...

I think and I could be wrong, but Back pressure doesn't effect turbo's as much as a NA engine...

[scottp999]

Your warranty is going to depend much on your relationship with your dealership (tech and SA). There is always a risk of a bmw field engineer being there at the same time your car is.

Do you have the 6/100k warranty, or will it run out in 12-18 months anyway?

There are exhaust options to remove all cats, some cats, or replace them all or partially with high-flow cats.

How far do you think you are going to go with modding the car? If you will upgrade to JB3 2.0 and do an intercooler, then you may want to consider going catless or close to catless to get the full performance out of the car. If you are sticking to JB+ (330-340whp) then I would keep everything easily reversible (especially if concerned about warranty), like you have it now. JB+ and DCI are quick to take out.

I really don't care about the warranty, so I am going all out with mods.

[Sal Collaziano]

I have a good relationship with my SA but I don't know anyone in tech..

I have a CPO warranty to 100k miles.

I know the downpipes will probably be enough to make people curious but maybe to play it safe, I'll just go with high flow cats. Aren't there secondary cats and resonators or something? I think I can get rid of those... There are no inspections in Florida so I'm probably fine without cats at all but I think high flow cats will be okay..

As far as mods - all I'm really interested in is the JB3, intake, exhaust, intercooler and maybe a high performance oil cooler since my car didn't have one to begin with - but I don't know because I really don't plan on doing any drag racing.. I just want to have more power than the typical modified Mustang GT or Camaro SS.

[Sal Collaziano]

Would a pair of three inch down pipes basically replace the main cats? Then, if I wanted to, I could replace the secondaries with high flow cats. Correct? Isn't there something else in there as well that might be replaced when doing a full cat-back exhaust along with down pipes?

[SV Concepts III]

You can purchase downpipes with high flow cats if you are concerned about retaining cats for smog reasons however this will not maximize flow. I suggest looking into the AA or ar design downpipes as they are the more popular setups on the forum. The brand choice depends on what you are looking to get out of the system.

We have the Active Catback setup on our 335 and it is a good choice for a midrange system. I also suggest looking into the Meisterschaft system which you can do with the connecting pipes for a complete cat back setup.

[Sal Collaziano]

Originally Posted by Nick@Jlevi SW

You can purchase downpipes with high flow cats if you are concerned about retaining cats for smog reasons however this will not maximize flow. I suggest looking into the AA or ar design downpipes as they are the more popular setups on the forum. The brand choice depends on what you are looking to get out of the system.

We have the Active Catback setup on our 335 and it is a good choice for a midrange system. I also suggest looking into the Meisterschaft system which you can do with the connecting pipes for a complete cat back setup.

When you say, "midrange" system, that's probably me considering I'm only looking for about 400 whp.. Correct? That being the case, I'd like to go with these 3" downpipes deleting the main cats and replacing the secondaries with high-flow cats and then a three inch exhaust throughout..

What about resonators? Do I have to worry about them or can they just come out as well? I'm assuming if my BMW dealership isn't very happy about any of this my exhaust warranty could be voided but I'm not sure I care. I just don't want any surprises.. Does anyone foresee any?

[ryan@ActiveAutowerke]

Active Autowerke'S Signature 335i Exhaust



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Large inlet pipes with super high-flow design


Active Autowerke's N54 Downpipes



The Active Autowerke Signature down pipe is designed with the intent to makes the most in power. The down pipes are created with the least amount of restrictions possible by utlizing a full 3.00" piping throughout with the least amount of bends and mostly straights where possible; that is impressive when compared to the factory diameter of 2.50". What you will experience is a faster, more responsive engine because the turbo impleller now has the ability to spool that much faster. The end result is more power


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[SV Concepts III]

Originally Posted by Sal Collaziano

When you say, "midrange" system, that's probably me considering I'm only looking for about 400 whp.. Correct? That being the case, I'd like to go with these 3" downpipes deleting the main cats and replacing the secondaries with high-flow cats and then a three inch exhaust throughout..

What about resonators? Do I have to worry about them or can they just come out as well? I'm assuming if my BMW dealership isn't very happy about any of this my exhaust warranty could be voided but I'm not sure I care. I just don't want any surprises.. Does anyone foresee any?

By midrange, I am referring to sound output. Most cat back systems, if designed properly, will yield similar outputs. The main difference will be in the sound output...some mufflers have packing while others are a straight through design for an extremely aggressive sound. We are running this system on Jon's 335 which is pushing well over 400HP.

[Sal Collaziano]

Thanks, guys.. I will come back to this after I see my service advisor.. If he tells me that catless downpipes won't be a problem, I may get 'em done... But I may just scrap the idea altogether. I'm learning that I'd need a modification to my JB3 to make up for the fact that I won't have an O2 sensor. That would fix things while the JB3 is in, but then I have to take it out for service - and then I'll have a problem again. It's a whole lot of hassle.. Maybe I'll keep this car until after it's paid off and really play with it THEN.