Custom exhaust shop recomendations and exhaust specs

[zcenterb]

Hey r3v,

So I recently completed my S50 swap into my 91 325i and was just curious if anyone on here new any reputable and experienced exhaust shops in the vermont/New England area that work with stainless. I'm located in Burlington, vermont, but I can trailer it somewhere if need be.

Also, I'm unsure of what I want the whole setup to be and was curious what people had experiences with or did/didn't like. So far I have rangeland long tubes the I have to get modified to clear the tranny, and I have a stromung catback. I was thinking 3 inch single pipe and maybe a borla mid muffler or something, but wasn't sure if I would have enough back pressure etc. let me know your thoughts. Thanks, I appreciate the help!

Zach

[justin_l_]

Unless you plan on going forced induction 3" is overkill. I would just stick with 2.5.

[zcenterb]

Yea, I figured 3 might be a bit much but I wasn't sure. Will it be too loud with just the race lands into straight pipe into the muffler? Borlas mid mufflers are only like 150 bucks... And I don't want it to be to uncivilized... I'm running the 3.5 HFMas well

[agent]

Will it be too loud with just the race lands into straight pipe into the muffler?

Probably. I have a Magnaflow dual in / dual out cat (now with broken baffles!) and it's bordering on too loud for daily use - I don't drive it every day though. I'll be replacing that with E36 M3 resonators at some point.

[zcenterb]

Yea I was thinking like borla or super sprint cats if I really want to make it expensive

[justin_l_]

I had a 2.5" borla muffler magnaflow cat and supersprint reps and it wasn't bad. My roommate has 3" vibrant muffler and resonator with supersprint reps and his is only slightly louder for reference. With no car or resonator it may be too loud for dd use.

[Bimmerman325i]

If you do the raceland headers on an s5x with the m50 manifold, you will have no torque until 4k. The exhaust diameter plays less of a role than you think on these cars. Unless the car's main role is to be a track/race car, run a 2.5 or dual 2.25. The issue is not backpressure but the resonance between the m50 manifold and the raceland headers. This resonance is at its worst, slowing airspeed dramatically, around 3500rpm. Look at dynos of s5x cars with m50/raceland/euro ss headers. Huge torque dip between 3k and 4k. This dip is commonly attributed to a lack of backpressure but it goes away entirely with different headers of comparable diameters. This dip is present even with stock e36 exhaust mated to the raceland headers, to a lesser extent.

The larger diameter exhaust improves flow at the expense of noise. Without cams, a 3" is overkill. I would go with a 2.5 if you really want a single, otherwise dual for good flow and silence.

I went to a resonated/muffled 3" with turner shorties from bone stock 95 m3 exhaust and gained power and torque everywhere, but it sucks on the street because its so damn loud. Go 2.5 with those headers.

[zcenterb]

Good info, thanks for the tips guys. Any experience with any exhaust shops in New England that will work with stainless pipes?

[zcenterb]

Also bump for being the new own of a 91 IX for $1400. Even came with a spare working transfer case just incase i ever need it...

[justin_l_]

Most exhaust shops will do stainless piping but still weld with a mig and steel wire so it defeats the purpose. Your best bet is to find a shop with a tig welder and buy the piping yourself. Especially if you want mandrel bends, shops with mandrel benders are very limited.

Do you plan on driving the car year round or summer only? If it's only going to be a summer car I'd recommend just getting aluminized steel piping and paint it. It will still last a long time and you will save a good chunk of change.

[M3PO]

I have eBay headers, 18" glass pack, 50 state legal cat, and borla muffler. All 2.5". Sounds nice and the volume is very reasonable. No rasp.

[Liquidity]

Unless you plan on going forced induction 3" is overkill. I would just stick with 2.5.

Single 2.5 for an M3 motor? That's less flow than factory.

[zcenterb]

It going to be the summer car yes. With some tracking on the side but not too often. My IX will be the winter beast. And i was looking to get mandrel bends and at least one V clamp or something to make it separate pieces. Heres a picture, race lands aren't on yet, i have to get those modified to clear tranny...

[butters]

Just call every place around you and ask if they can TIG weld. If they can, I think it's fairly safe to say they'll do a decent job of it.

A single muffler is probably going to be too loud. I had UUC's System U muffler and then added twin Vibrant resonators and their metallic high-flow cats when I switched to all stainless twin 2.25" - still too loud. Changed later to Dinan's muffler and it's much more civilized without drone on the highway.

[digger]

Single 2.5 for an M3 motor? That's less flow than factory.

its surprising how little a single 2.5" exhaust restricts things. the things that are more restrictive than the actual piping are OEM catalyst, resonators and mufflers so you wouldnt use an OEM 2.5" setup.....but an aftermarket custom 2.5" with mandrel bends but with a metal cat, bottle resonator(or another smaller muffler), and straight through large volume long muffler at the back you can probably make 300hp without having alot of hp losses and not be excessively noisy.