Help me choose a diff ratio...

[Stefan]

Trying to decide between 3.9 or 4.1 for my GA65. Trying to weigh up any benefit from taller gear/load versus revviness.

* Stock with 22RE was W55 + 3.58, which is very much the same as W58 + 3.9
* I swapped a W58 in with the 1G, didn't realise at the time it was so much taller. Currently have W58 + 3.5, which is stupidly tall.

Engine has light flywheel setup, single turbo (currently swapping from KKR430 to a smaller more responsive GT2530), bigger TB etc.. so it breathes well and likes to rev. This is a street car...

[JustCallMeOrlando]

3.9:1 is perfectly fine for what you describe, which is why I chose it myself. Mine was obviously a street car too. I'd be choosing it for just the slightly lower revs at cruise, but ultimately, it's not a big difference.

[Stefan]

Cruise is actually where the difference is least - I want the best at lower speeds.

IIRC xA6x Supra has slightly larger stock tyre diam?

Have never quite got an conclusive answer on the taller gear/load/turbo thing.

[JustCallMeOrlando]

All I can tell you, is that 3.9:1 was pretty much perfect for everything I wanted in a street car when strapped to a W58. Motorkhanas, drags, spirited driving. Anyone who went for a ride in the car would tell you it didn't really suffer for response.