[gameson]

Originally Posted by dís_f30

6.5" works the best with no lag. If you upgrade the internals (camshaft, rods, ported polished heads, etc.) then you could go bigger.

nah, just stock internal everything. the only things i replace are vrsf intercooler, go fast bit diverter valve, and all the pipes (down, charge, turbo, inlet) since i m running bm3 stage 2 and don't want to risk engine failure due to pipes failure. an insurance i would say

if i m investing that much more to go fast, better put that money and buy a car with bigger engine (330i with n55 or 340i with b58)... mods don't add much value to the car

[ATL_Nak-Muay]

Not specific to bmw, but I've put fmic's on lotsa builds and it has always dropped the boost a hair. Just my experience.