i've seen far more people with 3.73's than with 3.90's
the diff between 3.9 and 4.1 is gonna be like less than 100 rpm man, why not just go for 4.10 if it's mostly around town or drag strip, and 3.73's if you're gonna see some highway in it.
little off topic... i love my 3.55's, first gear in the 3.35 t5 is just perfect, i think if it were any shorter i'd not like it so much.
I currently have 3.55's and they were just about perfect with the stock 3.35 T5. Now I have a 2.94 1st/.59 5th and now the 3.55's are much too steep for the power I'm making (240/285 @ the wheels)
If the RPM diff is that little, I'd like to just get the FMS 4.10. I'll do the calculators again and check.
sounds like a plan. from what i've heard, the 3.90's haven't been around as long and aren't made by most of the major gear manufacturers right? i'd go with something tried and true when it comes to the rear end