Custom Performance Engineering prototyped a stainless steel catback exhaust for the 335i. It features nearly 27ft of premium semi-polished stainless steel, two resonators, and two mufflers. We're showing the catback kit, and the BOV this weekend at the DC BMW meet if anyone is interested in hearing the car first hand.


Stock mufflers:

http://www.mustangmods.com/ims/u/535/644/110565.jpg

CPE mufflers:

http://www.mustangmods.com/ims/u/535/644/110561.jpg


Stock middle:

http://www.mustangmods.com/ims/u/535/644/110566.jpg

CPE middle:

http://www.mustangmods.com/ims/u/535/644/110563.jpg

New resonators:

http://www.mustangmods.com/ims/u/535/644/110817.jpg

Another exit shot:

http://www.mustangmods.com/ims/u/535/644/110560.jpg


Look at all the bends and crimps in the stock exhaust:

http://www.mustangmods.com/ims/u/535/644/110567.jpg



Some sound clips:

From outside: http://www.youtube.com/watch?v=Q2VrWXUmtFk
http://www.youtube.com/watch?v=68Ht8ZzOyHg
http://www.youtube.com/watch?v=r8dVDABpiK0
http://www.youtube.com/watch?v=8i9X7xIKmFk

From inside: http://www.youtube.com/watch?v=7o5xTtUG3uw


The BOV kit replaces the two plastic diverter valves with a billet aluminum Tial BOV. Pictures and video below:

http://i7.photobucket.com/albums/y285/aznevoviii/IMG_0001.jpg
http://i7.photobucket.com/albums/y285/aznevoviii/IMG_0006.jpg


Video clip: http://www.youtube.com/watch?v=gn1af3gyScA


We're curious to hear what you guys think. What do you like or dislike about the kits? Anything you would want to see changed for the production version?

Jordan

Unles I could not see it, you are missing something crucial, a crossover/equalizing pipe. The way you have the exhausts routed right now it looks like the pipes are never combined which means that in reality you have two 3 cylinder exhausts as opposed to one six cylinder exhaust. It does make a difference.

What's the dyno say?
But I'm excited!

Unles I could not see it, you are missing something crucial, a crossover/equalizing pipe. The way you have the exhausts routed right now it looks like the pipes are never combined which means that in reality you have two 3 cylinder exhausts as opposed to one six cylinder exhaust. It does make a difference.

Ah, good eye. I forgot to post a picture of the crossover.

http://www.mustangmods.com/ims/u/535/644/110818.jpg

What's the dyno say?
But I'm excited!

Good question, we need to get the car back in the shop, reinstall the stock exhaust, and then go dyno both systems. As soon as we get it done we'll post the results. Of course, I'd be surprised if it didn't make a good chunk of power considering the bends and the smaller diameter of the stock system. I forgot to mention our exhaust system is 2.5", whereas the stock system was 2.25".


Jordan

How much wider are the exhaust tips than the stock

how long till this thing hits production and have they figured a price out yet?

How much wider are the exhaust tips than the stock

Actually, the tips we chose for the prototype are 4" tips, but we're going to offer a variety of tips, since people seem to be very particular about what style tips they want.

So, if you have a particular style in mind, we're looking for suggestions. Post em up! This is the style we went with for the prototype however:

http://www.mustangmods.com/ims/u/535/644/110877.jpg


how long till this thing hits production and have they figured a price out yet?

We don't have a price figured out yet as we're still crunching the numbers. Our aim is to produce exhaust components that are on par, if not better than some of the "up-scale" German manufactuers. But, we'd like to do this without artificially jacking up the price simply because the market is up-scale and will tolerate it. We firmly believe we can produce absolutely gorgeous exhaust components without charging an arm and a leg for it. We will post pricing as soon as we work that out.

As far as a release date, we still need to fabricate the fixtures, so it will be probably three or four weeks before we could start selling anything. But we want to make sure the interest is there before we start working on fixtures and the like.

We've also scheduled a dyno session for next week, and we'll post the results here for everyone.

Do all of the sections need to be welded or are there clamps for certain sections?
In other words, could this system be installed by the owner or would I have to take it to a place to get the system sections welded into place?

Nice looking exhaust, I'm so tempted to get one once they hit full production. However, I'm just not sold on the BOV... it's just too ricey for my taste and the constant air relief agitates me after long drives. Very cool but not my thing.

i don't like BOV, and 4" is too large for my taste

I'm surprised that 4" tips fit. Vishnu implied that there was little room for larger than stock tips. Did you have to mod the bumper to get the cutouts to match the 4"'ers?

I wouldn't mind a BOV if it only sounded when I was winding out the engine. Are they perceptable in normal driving with every shift?

Do all of the sections need to be welded or are there clamps for certain sections?
In other words, could this system be installed by the owner or would I have to take it to a place to get the system sections welded into place?

I'll see if I can snag some more pictures, but there are a couple clamps. This was designed to be a bolt-on system.


i don't like BOV, and 4" is too large for my taste


We totally respect your opinion, which is why we'd like to hear which tips you do prefer :cool


I'm surprised that 4" tips fit. Vishnu implied that there was little room for larger than stock tips. Did you have to mod the bumper to get the cutouts to match the 4"'ers?

I wouldn't mind a BOV if it only sounded when I was winding out the engine. Are they perceptable in normal driving with every shift?


We're actually not positive on the 4" measurement. We'll measure it directly this weekend.


Jordan

Love the sound inside, love the sound approaching. The sound as the car was moving away was a little too wurbly/throaty (read:not smooth enough) for my tastes, though still sounded good. Also, the low RPM sound was kind of like WTF is that, though I don't know how much of that is exhaust and how much is intrinsic to the engine. I don't like huge exhaust tips but thats not important since you said you'll offer a variety of tips for the kit. And I hate BOV/ricer sounds so I won't comment on that :)

Overall, me likey.

Love the BOV, when will this part be for sale? I assume u can pump that out quick and cheap.

On the exhaust tips - I'd like to see a very close facsimile to stock (I'm going for the sleeper approach)

Overall on the exhaust, maybe try another cross over following closer with the factory towards the end of the exhaust run to even out some of that sound, but not too bad. Very interested in cost, and quick q is it true these cars use a system to only open both tips over a certain pressure?

Your performance cat-back system looks amazing! Keep up the good work and definitely post us the results of the dyno tests! Love the BOV too... :D