[JimD]

I am pretty sure I was looking at a e90 which I believe started in 2006. In that year, the 325 was a n52 rated 215hp and the 330 was a n52 rated 255hp. Later the e90 went to the 328 and 335 nomenclature.

Magnaflow makes both a cat back exhaust for the e88/82 n52 and replacement exhaust manifolds with catalytic converters for the 330 n52. I am theorizing that the 330 manifolds might fit (?) or magnaflow might offer replacement catalytic/manifolds for our cars. The replacement manifolds with the cat back should get us to at least 255hp (with intake manifold and probably some tuning).

The observation, which makes most sense if you look at the nice diagrams on realOEM, is that replacing a catalytic converter on our cars involves either a lot of cutting and welding or a replacement exhaust manifold. It is not unusual to have to replace a catalytic when a car gets up around 8-10 years old. So it was not surprising to see Magnaflow offering replacement manifold/catalytic converters for an early e90.

Jim