What LSD ratio?

[Uber E30]

If you're staying NA on the stock getrag but want more pickup I would say 3.73 is a good ratio without making the lower gears totally useless. If you're going FI then you actually want a much taller diff to stay in boost for a long time, like a 3.15.

[Breticus]

I think I'll do the 3.73 then. When I do my swap I'll make sure I get the right transmission to go with it or even maybe to go with the 2.93