Hi All,

I'm looking to upgrade my diff for better acceleration. I've heard of e30 M3 guys using a 4.45, but has anyone tried a 4.56 or 4.75. I've got the typical 4.10 diff from and M3 but I'm looking to build one with more aggressive gears. With the 4.10 I'm primarily using only 3rd and 4th gear, and occasionally 5th on tracks with very long straights.

I've run the gear calculators and the 4.75 would give me a top speed of 120 MPH. It would also give me 3 usable gears on the short tracks instead of just 3rd and 4th. I'm very tempted to go with this gear but curious if there are any major drawbacks. Someone commented to me that 5th gear (.81 overdrive) is a weak gear. But I figure that it would still be rarely used, and the really low ratio would compensate for this.

Any advice or shared experience with this would be greatly appreciated.

Thanks
- Nate