Exhaust Advice 135i

[blklacker]

Any good FYI threads on exhaust. I didn't find much in the search.

#1 I don't want to throw any codes.. but I want throaty exhaust that provides decent hp gains with SSTT. I'm defiantly going with a cat back system staying on the safe side. I have a local performance shop in my area they are quoting me $600 for the job.. They are providing the materials.. Is that price too steep.

Here is my plan... I'm going with a single 3" pipe with a Y at the end. I'`m considering going with a 3.5" with a Y at the end. Are Down pipes worth it??? Guys I need your input on this MoD.. any suggestions or information that I should pass on to the performance shop. Any feed back or words of warning would be greatly appreciated.

[MrRoboto]

I am strongly leaning toward the RR Down Pipe only.

http://www.1addicts.com/forums/showthread.php?t=10591

[BMW135iCA]

How loud do you want your car? How much performance gain do you want? If you get catless downpipes and remove the third cat when you get a catback you won't pass smog test I would assume. Personally if you want to get a catback high flow cat downpipes would be good. I also would not get new downpipes without some sort of tune. In my opinion it would be safest to have the computer running to the fact you have different downpipes they allow more flow.

Chris

Chris

[Bullitt]

Have you considered the BMW Performance Exhaust? Downpipes are worth it, especially if you don't mind the louder sound levels. A better exhaust may not be as beneficial as better downpipes, but it still helps. A combination of new DP's and a new exhaust will help a tune to perform even better.

Read post #38 and #39 in this thread: http://www.1addicts.com/forums/showt...071#post175071.

[Bullitt]

Originally Posted by BMW135iCA

I also would not get new downpipes without some sort of tune.

Why? Downpipes may be better utilized with a tune, but they still provide notable performance gains without one.

[jeremyc74]

Originally Posted by Bullitt

Why? Downpipes may be better utilized with a tune, but they still provide notable performance gains without one.

On older turbo cars there was the possibility of tuning issues after a drastic change in the backpressure on the turbo (such as removing cats). It could throw off the A/F ratio for one thing.

The ECU on this car seems to be pretty adaptable from what I've read, so I'm thinking it's probably not an issue.

[1er junkie]

Originally Posted by jeremyc74

On older turbo cars there was the possibility of tuning issues after a drastic change in the backpressure on the turbo (such as removing cats). It could throw off the A/F ratio for one thing.

The ECU on this car seems to be pretty adaptable from what I've read, so I'm thinking it's probably not an issue.

+1

[mikeo]

blklacker, on the plus side $600 seems very reasonable for a custom exhaust. On the downside, you really have no idea how it will sound when completed.

[blklacker]

Will custom DP throw any codes?

So guys needing your help... Im at the cross roads of either going with custom Down pipes or Cat-back with 3"-3.5" single pipe with a Y at the end I do not want to throw any codes any feed back would be appericated or any information I could pass On to my exhaust foreman. I'm currently going to be using SSTT as a MOD with air intake mod later down the road.

[mikeo]

I would avoid a custom DP. Since the primary cats are in the DPs 1) catless will throw CELs, and 2) If you want DPs don't re-invent the wheel--buy Riss Racing or Ultimate Racing DPs and a SIM to prevent CELs.

[blklacker]

Any info on replacing cat converter with a resonator??? will this throw codes?

Thanks for the Info. Does anyone suggest an after market cat converter. I decided to take this project in steps. I'm going with a basic cat-back system still leaning on replacing the OEM cat converter, If i feel the need for more I will investigate Riss racing down pipes, that video sounded pretty dame good. Does anyone have a good pic of Stock OEM exhaust... thanks guys main goal is to get good performance without throwing codes

[ML]

Look for a catted downpipe in stead of catless. I believe that both companies previously mentioned make downpipes with high flow cats.

[EODGUY]

Who is doing your work? There are, or at least were, very few shops in WA that were able to do mandrel bent exhausts. Going with a crush bent exhaust really won't do you any huge favors as far as performance, because even if you increase the size of the pipe, some of the crush-bends can actually be more restrictive than your original exhaust.

You can, however, work with the shop thats doing the work to figure how many bends there will be, and what angles they need to be and buy mandrel pre-bent sections that can be welded into the exhaust.

[jeremyc74]

Originally Posted by blklacker

Any info on replacing cat converter with a resonator??? will this throw codes?

Anything other than a catalytic converter is going to throw codes. Even a high flow cat may throw codes.

[mtla4]

x2 600$ is a good price.Id rather get a full line than the BMW performance

[blklacker]

Originally Posted by mtla4

x2 600$ is a good price.Id rather get a full line than the BMW performance

The company is asking me if I want a muffler or not. ......Should I get straight pipes from the Cat converter with out muffler???

[mtla4]

Well theyre probably talking about a resonator. It depends honestly this car is not my daily I cant careless if it sounds bad or loud I want the more performance out of it. For the general public bigger piping+resonator+flowmaster muffler+nice tips=call it a day. I guess it takes some guinea pigs to lead the way do it and let us know how it goes.

[blklacker]

fudge it.. im telling them to fit a 3.5" pipe at the end of the cat converter and run pipe to the end with a Y joint + nice tips if im not happy I will address the cat converter and the two resonators before the Cat.. at a later date.

your thoughts?

[new2the3]

use a muffler but no resonator...

[blklacker]

Originally Posted by slm95

use a muffler but no resonator...

Decided on just cat back for now and Down pipes Next time around.

[BMW135iCA]

Here is something to think about. I don't know if this would happen, but say you get pulled over for a loud exhaust etc, and the police pull you over and look under your car. If you get a catback it will delte the cat that is visibly seen, and you may get a huge fine for that. That is why I am almost thinking of catless downpipes with an axelback so I can keep that one little cat.

Chris

[mtla4]

The only way to see that a car has no cat is send it to inspection. Most of the cops dont have the ability to check or are just too lazy to crawl under. They wont pull over a Bmw(like they do with Honda-Acura so I dont see a problem with no cat.