Ken, one thing I forgot to ask... What year X3 can the 3.91 Diff come from? Thanks George.

great ken, thanks for talking out of the nitrous lol. think ill just work on getting the 3.91 for now and save the 3.38 in case I gotta convert back for a manual. I dont think a zhp rear would be much of an upgrade to be worth it with an auto. One last question for now, are you able to kick M3 ass with the AA SC and 3.91's?

Your 330 already has a 3.38 if you're an auto, so a 3.91 is the only thing worth swapping in. You can try to find a 3.64 out of a ZHP so it's still manageable if you go manual. Nitrous is cool, but not worth it...it works out to be expensive in the end because you have to constantly spend money to refill it, and it's not instantaneous power. The bottle has to heat up for full pressure/power, and it's not on all the time. That's why I went forced induction.

Whats up kenny, its me george; hey, I have a few plans to go to a 3.91 diff from an 2.5 liter X3, but was wondering if its a stupid idea in cause my trans blows and I go manual; maybe I should just go manual with the 3.38? Also, Im serious about a nitrous 50 shot set-up(just because the AA is too damn expensive) was the nos worth in your opinion? if so why did you go SC in the end? I have headers and a cai, so I was thinking a 50 shot and 3.91's plus a tune (software) would be nice. whats your opinion based on your experience?