Originally Posted by red_wagen
I meant tuning it so that it puts out 255hp like a 330i. The 328i is the same engine so I presume adding the missing components and reprogramming the ECU will do the trick, yes? I don't know how much trouble it would be to do and at a certain point it might not be worth it for 25hp only.
There's been a couple of threads on trying to make a 325 or 328 into a 330. I can save you alot of reading. The cost and hassle associated with all the stuff makes it prohibitive. There's more to it than the throttle body, intake manifold and ECU. But feel free to search and see the tech explanations.