[E90Vader]

Since I saw a few posts with questions about this, I also had the same question! I thought I would make a thread specific to this!

Come tomorrow, I'm going to phone a few local muffler shops and see if they have the capability to build straight pipes for my 335i from the DCI back.. This will remove all cats ETC.

If they are able to do it, what diameters should my customer exhaust have?
I.e will I be okay going 3" all of the way back, or should I have 3" down pipes / cat delete with 2.5" piping from the cat delete back?

Looking to get the best free flow / performance from this. I know it will sound ridiculous but it may also save me a good chunk of change and give my bmw a one of a kind unique sound compared to all of the name brand exhaust set ups out there.

Help would be great guys!

Please also feel free to post your experiences and clips to BMW's with full straight pipes all of the way out of the back of the car for others to see.


As soon as I get some quotes from the local shops I'll post them up here so people can get an Idea how much it will cost!

Also, what material should I use? Stainless steel?

[gtenedio]

Whats a customer exhaust??

I dont know what your looking to spend nor do i know what u have been quoted- but if i read correctly- ur doing "custom" downpipes as well....that might get pricey...as for the exhaust- i would do 3 inch all the way back. Not sure what type of sound your looking for but straight pipes all the way back with just the mufflers is going to be LOUD. i would have them throw on 2 resonators or another set of mufflers on there. Just my 2 cents though

[gtenedio]

Custom downpipes aside...a custom exhaust from the downpipes back shouldnt cost anyone more then 500-700 with the exhaust tips. Now, i can guarantee you that if ur doing custom downpipes too- the shop will quote you close to 1000 if not possibly a little more.
And the exhaust is turbo back not dci. Your exhaust doesnt start from your intakes...............

[E90Vader]

Custom exhaust is what I meant.
I apologies about stating exhaust from the intakes.. * I know very little about cars and I'm slowly learning *

Is it still the cheapest and most cost effective to purchase AR Catless Downpipes? a muffler shop will charge me a little less I will go that route, as well as straight pipe all of the way back. One of the tuning shops here quoted me 6 - 700 just to install a catless down pipe so It might be cheaper to go to a muffler shop and have them build me one and install it all in the same show.

I understand it will be LOUD, but performance wise there will be zero pressure spots, and it will save me over a thousand bucks I'm hoping. I'll find out after I make a few phone calls.

[JayKay335i]

In reality you wont be saving anything because you can pick up a used exhaust for the same price or less. Custom down pipes will definitely cost you more than a couple hundred dollars. You can buy downpipes anywhere from 2xx+, depending on brand, fitment, quality, etc. If you buy downpipes and then have a custom exhaust made the easiest thing to do would be to use the flange from the OEM exhaust where it connects to the DPs and go from there back at 2.5".

[E90Vader]

So pick up a set of AR Catless downpipes, then just get a local shop straight pipe 2.5" back from the DP? Thanks for the good advise guys.
What should I use for muffler tips if I get the shop to make straight pipes? Just have them fabricate a big tip for me?

[blisstik]

It's just best to buy something that was developed to be bolted on. For a custom exhaust, you're betting on the shop's skill and quality. It's also a lot harder to resell custom exhausts.

[UFhypzM3]

cut off the mufflers and get catless dp's and call it a day...exhaust on our cars is really just for sound, it adds little performance wise.

[turb0mik3]

Originally Posted by UFhypz335

cut off the mufflers and get catless dp's and call it a day...exhaust on our cars is really just for sound, it adds little performance wise.

Eh, I wouldn't go that far. It does add up in the end, probably around 10-15whp with a tune and full mods. Plus the secondary and primary cats are pretty restrictive, not to mention the resonator if you have an e90. Custom exhaust are ok for older cars imo, but for a BMW if is good to get mandrel bent exhaust items that will last longer. Just my $.02. Save up.

[E90Vader]

I'm hearing about these secondary cats, where are they?
If I get AR catless downpipes, that eliminates the main cats. What do I need to eliminate the rest of the cats?

Also how do I cut off the muffler? Won't I have to replace the tips with something?

Can we do a quick 5 min exhaust review, what parts are what!?

Ultimately as well I want catless dp's and straight back exhaust just like HFP without spending 2K on exhaust and another 800 for dp..

[fire_mike]

Is there any way (besides the golf tee mod) to get more sound that is an easy bolt on/off? I'd love to have a bit more sound from the exhaust (not a ton though), but I also don't want to screw my warranty. If it was something that could be changed rather easily - like in 30 min or so - I'd love to do it.