E46 330Ci - E36 manifolds on m54b30. Tune Required?

[i.mulhern]

So I finally got around to installing a subframe that I put Condor bushings in. While getting ready to remove the exhaust, I realized just how bad the bolts in the exhaust flanges from the manifold to the rest of it where. Stock, heavy ass exhaust : D. So I cut it into a muffler section and mid section with a sawzall, leaving some pipe after the manifold - catback flanges expecting to use couplings to re install it. A 2" coupling fit perfectly on the mid pipe to muffler pipes, but after the manifold to catback flanges, the pipes are a little different in size from side to side. One a little bit bigger than 2" and one a bit smaller than 2". Putting it back together with whatever works doesn't appeal to me. My question is this. I've wanted to use a TMS Spec e46 exhaust for a while now all the way up to the e36 manifolds. Will my car run like shit with e36 manilfolds and a full exhaust without a tune? If it will run fine, could I hurt the engine? What is the go to oxygen sensor setup? I don't know how the engine management would react to no post cat. sensors. The car is otherwise stock. TIA

[pbonsalb]

It will run fine, but if you want much more power, run a catless mid section. If you BBC want to go all out, run aftermarket headers, midpipe and rear exhaust. The euro spec MHD and rear use 2.375 to 2.5 inch piping versus 2.0” for the US cars. The headers also differ so you need to go all US or all Euro or fo done custom cutting and welding to connect the parts if mixing and matching US and Euro. Figure that BMW determined the Euro parts were a good all around choice for 321 hp, and the smaller US counterparts were a good choice for 240 hp.

[i.mulhern]

It will run fine, but if you want much more power, run a catless mid section. If you BBC want to go all out, run aftermarket headers, midpipe and rear exhaust.

So I never realized that Bimmerworld designed the Spec e46 exhaust, and magnaflow made it. I now have a complete spec e46 exhaust system, manifolds and install kit. I waited about two months for it to show up. I bought the exhaust through Morehead Speed Works, and had already picked up some stock S52 manifolds that I will assume are US spec. The 02 sensors that are in the stock manifolds right now on my car are about a year old and probably sniffing just fine. Almost 160k miles and the old m54b30 just went through Maryland emissions with no CEL and a sawed off muffler. Sweet. I have some terrible oil leaks to fix and a manual transmission swap to do, to do the exhaust justice. It is a very nice piece, and worth the wait.