Quote Originally Posted by ZHPizza View Post
Well I am trying to move forward on this project and ran into an issue. Just posted on e46f so copying it here in case anyone is considering this...

So I thought I would be able to pull this off without modifying the OE midsection, but it turns out I can't shorten the rear M3 header enough to fit the OE connection. I'll have to modify the midsection too to move the flanges downstream a bit.

S54 manifolds:

M54 manifolds:

Front comparison - for this one, the S54 pipe COULD be shortened enough to make the M54 flange location work:

Rear comparison - but you can't do the same with the rear:

The S54 cat extends into where the M54 flange is, hence the need to move the flanges downstream a bit on the misdsection:

The guy on e46f saw this and moved the midsection flanges down and shared these pics of the finished product:

I just sent these to my buddy that's doing the fab work and I guess I'm taking him the whole damn exhaust on Monday
If you manage to make this work then I might do the same...

Sent from my iPhone using Tapatalk