Originally Posted by Tom Koh
Gents - I didnt want to start the N51/52 conversation - the intent here is to see who has found the best intake + ECU + exhaust setup to make the 128 a couple tenths faster. Based on all of the reading I have done, the 3 stage intake (NOT the one on the N51) is one of the core components that the high output N52s (e.g. 2006 330i E90 Sedan) uses to achieve 255 bhp vice 230 bhp.
JAF89f - Yes, the 128i stock is a pretty great setup, especially for autocross - thanks for posting a comment telling everyone posting comments about this is not worth the hassle.
This guy upgraded his 325i (an even more detuned N52) to ~260 hp and ~225 ft lbs (crank, correcting for drivetrain loss, compared to 230 hp and 200 ft lbs). He and has info on the manifold DIY (pretty much the same engine, so it should be similar..) and the 330i intake he used..
If you wanna go crazy, you can also go this route. Some guy's 323i put down 291 hp