Dear 556129,
I am sorry for the late reply. Have been enjoying my manual transmission. Yes, you can definitely fit a manual transmission to your 330i. Talk to Ah Wai, he did a wonderful job for me. Nothing dodgy. I never realized what a parasite the auto transmission was. Now with it gone, the engine is much more relaxed. Gear changes are smooooth. The pick up is much much more and you can use each gear to its fullest potential. Ah Wai has put a getrag transmission for me, smoother than the zf.
The zf on the other hand is heavy duty, and is the way to go if you want supercharging or turbocharging. But honestly, unless you're a track racer, not necessary la. The cost is from 12 - 14 k, worth every penny. I chose the manual path because I do tend to drive heavy footed and like long distance driving especially hill climbs. I dont think the recond auto can withstand for long. Go talk to him, pick his brains.