New 330Ci Exhaust
 

I have an 02 330Ci and I wanted to replace the muffler with straight pipes and magnaflow tips.

My question is I noticed on RealOEM.com that there is a vacuum control exhaust flap. Has anyone run into issues when removing the muffler and what is done to account for the vacuum control flap? Do I just need to tap this into the new striaght pipe or is that necessary..
http://www.realoem.com/bmw/diagrams/o/r/127.png
This is a video of exactly what I want to do and you can see the straight pipes welded in and tips added.

http://www.youtube.com/watch?v=QryxD5m7v1E

A few other good videos:
http://www.youtube.com/watch?v=Qqqwu...eature=related
http://www.youtube.com/watch?v=EyUji...eature=related


I wanted to go with this dtm style tip since there isn't a cut out on the stock bumper I think it would look nice with the angle:
http://images.magnaflow.com/02product/parts/35133.jpg

So here is what I am looking at getting quoted at a local custom exhasut shop.

Both are custom exhausts, but one keeps the dual tubing and stock size 2.25". It just removes the front silencer and muffler.

The Second one is more of a custom Catback. It will have a Y pipe that goes to a 3" exhaust all the way back to the rear. This will get rid of all resonators and muffler. Obviously this will be more expensive but it would be nice to see what it would cost and compare to other cat back systems.

Just out of curiosity I would like to go to a single 3" exhaust to reduce back pressure. Do you think the y pipe will cuase any extra back pressure.

You can definitely just remove the muffler all together and install tips on the end. You can also leave the resonators and just remove the muffler... that's what I did with my setup and just routed piping/tips to both sides of the bumper... here is an old vid

http://video.google.com/videoplay?do...om+exhaust+e46

Just so you know none of those videos are of strait pipes, they simply have the muffler removed not the two resonators, also true strait pipes would include the removal of cats

That sounds nice! It's definetly the cheap and easy way, but I am debating if I want to touch the stock exhuast.

For the custom exhaust I am looking at putting a 2.25 to 3 reducer to mate up with the cat, then have a 3 to 3 y pipe with 3" tubing to the back with another 3 to 3 y-pipe. I was going to have the 2.25" tips cut back to the 3" dia and welded onto the y-pipe. This way it would be 3" all the way back from the cat! I could get the y-pipes for $55 and the tips are $90, so all I would need is a quote on the reducer and single 3" pipe to the rear. Did I mention it would all be stainless steel T-304! I want to keep the cat in but the resonators would be taken out.

I want something that sounds good but not like a full striaght pipe M3 exhaust sound.

All you have to do is plug the vacuum line with a screw or something so that you don't get a vacuum leak. I stuck a drywall screw in mine about 5 years ago when I did my exhaust.:)

Do ZHPs have the Vacuum control flap?

2000 328Ci, that system sounds mean! Very nice.

Redlin'r, I don't think you can go wrong with either option. One that you may want to look into (that I have heard in person and really liked) is going with a 2.5inch pipe set up, killing the resonators, and going with a Borla muffler. I'm not sure how much benefit or sound change you would get out of jumping that extra half inch to 3inches all the way back. You may loose some downlow oomph, and I really don't think the E46s that aren't forced induction flow enough air to justify a 3inch system.

Perfect! I think I have a few dry wall screws laying around hahaha.

This is a good point. I don't know if I will gain or loose much from a 3" exhaust. The major benefit of either exhaust is the weight reduction. I found all the parts I need on summitracing.com. All parts are stainless magnaflow (2 y-pipes: 2.25 to 2.5 and a 3 to 3, also a reducer from 2.5 to 3 and the dtm tips) The exhuast will mount off the cat and use existing clamps and the y-pipe would step it up to 2.5. When the reducer is added it will upsize it to 3in and be 3" all the way back. All I really have to find out is how much the 3" stainless steel tubing will cost and labor. I will but all other parts and those are much cheaper then I thought. I am almost tempted to dyno the car bone stock and then do a run afterwards if I go with the custom cat back.

Lets remember I am not removing the cat, so the headers and stock cat will be in the system. I don't see how a 3" pipe could ruin low end. If I remooved the headers and got rid of the cat then I beleive this is the case I would see. I am not expecting HP gains and as most people have said that I read this system would mainly benefit high end, the low end shouldn't suffer though.

Here's a good picture of the stock exhuast laid out....

For anyone intersted in backpressure concerns, read this. It is a simple write-up on the myth of reducing backpressure will reduce torque.

http://www.uucmotorwerks.com/html_pr...torquemyth.htm

I side with UUC on this write up. Since our cars have ECU's to adjust for more fuel consumption with less back pressure I don't see me going to a 3" exhuast for ~3-5ft to cause any problems. The restrictions are at the headers and cat so it will be minimal as well. I would be interested to base dyno the car and wideband monitor the a/f before to see how it the ECU adjusts the fuel for backpressure decreases.

I know a bunch of my turbo buddies have all said running an open downpipe, or at least a cut out, have all said they've noticed a lack of torque with the wide open exhaust, but tons of power up top. But I know things are different in more ways than any of us would care to derail the thread between turbo an NA cars.

If you aren't looking for performance, than a three inch full pipe would be fine, especially if you can get some awesome pricing on it. And if your keeping the stock headers/cat, then you shouldn't notice any losses, or most likely wouldn't loose anything then. Weight reduction will be huge.

Good luck with the system, and keep us updated. I wanna hear what it sounds like when you get it all done!

Back in the day when I had an STi I put a bellmouth downpipe and 3" exhaust on it and noticed an improvement in all rpms. The aftermarket downpipe allowed the turbo to spool faster and I actually had a problem with boost creep because the wastegate wasn't dumping fast enough.

I am not very familiar with N/A exhuasts but I did here that putting a FART can on a Honda hurts it more than helps.

I went and had a quote. I will purchase the parts (y-pipe, tips) from summit for ~$145. The muffler shop quoted me $120 for install and that includes the piping he would run. My original idea was to go with 3", but I am probably going to jsut go with 2.5". The sound will be just as good and I won't have to worry about power issues! I will have to wait for the exhaust tips to be in stock since they are back ordered and this gives me some time to figure exactly what I want to do and be happy with it.

I have a question about stock resonators and cats. Am I correct when I say the exhaust, in order, has muffler-resonator-cat- headers? I will definitely be getting rid of the muffler and resonator but I am wondering if that is a cat or another resonator closest to the engine. Are there any other cats?

From what I remember under my 325i, there are two cats in the headers. Then you have two resonators, and finally the muffler itself.

Yup your right! I checked realoem.com and sure enough there are cats on the headers. I will have the front one taken out as well then. Unfortunetly I have to wait until the exhuast tips are back in stock (it says they will ship 4/13).

What tips did you decide to go with? 2.5inch will give you a good sound and some good oomph. Can't wait to hear it when you get it all in.

Ok after a long debate I actually decided that I will just have both resonators taken out along with the muffler and straight pipe added. I didn't think it would make much of a difference taking the exhaust from to 2.25" pipes down to 2.5" then 2.25 at the tip again. So I am going to order my tips and get this done. When I decide to go with headers I may look into my custom exhaust idea and that way I won't step it down.

I won't have to worry about power loss and the sound will be good since that's really all I would get out of it. I might notice small gains on the top end but that isn't normally seen and I won't get to the top end at autocrosses hahaha.

Also the money I will save goes to my next mod: Hotchkis sways! I will keep ya'll posted on when I get the tips and post videos once it's done. I found someone on ebay that has them in stock and won't have to wait so it maybe sometime within the next two weeks.

Nope, and to the OP-if you straight pipe the ENTIRE exhaust, no resonators & no muffler get ready for one loud, raspy, & IMO obnoxious 330.