Originally Posted by andrey_gta
For internationals - find what engine you actually have: n52 or n53 and then search.
For USA/NA - 325i best benefit forma simple tune. Then you can think about anything else
This gets asked here often
Lots of answers for n52 here usually involve headers + free flowing exhaust, intake manifold from 330i, tune. keep in mind your regions emissions standards when doing anything with exhaust /headers
thanks i have an n52 i want to boost it but i cant find anything about the internals