Yup pretty much that, well one of my unscientific tests, I took the car from 40 - 100km/h in 3rd gear, with the standard 2.93 diff it took about 9.9s and with the 3.38 it came to 8.3s, though I wouldn't read to much into this, apart from the fact that there is an improvement. Also tested on my private testing facility, which includes a pretty long up hill the car reach much higher speed that in would normally do. (I like up hill cause it tends to show difference in output better)
Yup I would think 3.46, but this would only be to avoid having to change the input flange of the diff. From what I read all the six cylinder e46 apart from the 330i's came with 4 bolt input flanges, where the 330i came with a six bolt one.
For 3.46 you should look for either a 323,325 or 328i auto or 325i touring auto or manual. If I am not mistaken a diff out of any of these should be a straight swap into your car (might need to change output flanges as well, but that is not to hard)
Nothing is stopping you from going for something like a 3.38 will just be a bit more work. You can also go for something less aggressive at first you can also get a 3.07 or 3.15 out of a 323i and 325i manual respectively but I don't think this will make a massive difference as your current ratio is 2.93.
Thanks LZ :grin:
