Is OEM exhaust stainless steel?

[bignslow]

Like the title says is OEM exhaust made from stainless steel or not? I need to do cat back exhaust on my 91' 318IS. Just wondering if I should bother trying to source OEM stuff or if I am better off going aftermarket? I want stainless and I want it quiet.


If OEM is not stainless would someone know the exact muffler dimensions so I can source stainless replacement?

[nogapersnBMWs]

318iS m42 stock single tube exhuast ID = 2.25"/57mm. Sorry, IDK dimensions of muffler (although circumferance of muffler should be same as 325i/iS/iC as muffler strap same (18211707923) so you just need length numbers, LMK if you want circumference measurememts) or material of exhaust, never had pleasure to own a 318iS. As an aside, check PP in upcoming week Serge.

The only.stock BMW E30 exhuast that I know is stainless is for an M3.

If your m42 is stock = quiet stock exhaust. Unfortunately most of the cheaper stock style catbacks (Ansa, BOSAL, are made of aluminized steel which doesnt last long like more $ stainless). If plans are to heavily modift N/A m42, especially internally (stroker crank,.overbore pistons, cams, etc) = loud aftermarket exhaust (headers, test pipe/cat delete if for track), ceramic coated over stainless (based on thermal properties increasing exhaust velocity). The stock BMW m42 headers already nice though. If going F/I m42 obviously dont waste $ and time with headers, test pipe, etc

[jrobie79]

There's a group buy for a Stromung catback that is all stainless. Maybe you can reach out to them to have it it modified to lower the sound. It's not wicked loud as is, but it definitely has more grunt than stock