Don't know about performance increases, but since I put my PC pipe on I've gone to 40:1 Amsoil, and didn't change jets either, just moved the needle clip up one. I have a 01 220R. I think Amsoil is probably recognized as the top dog. Eight bones a qt though, ouch. I'm a 6 weekends a yr guy though so cost is irrelevant. I buy the good stuff since I only buy a couple jugs a yr. I do think it's a little crisper in 1st and 2nd since going to 40:1, but it could obviously be the new pipe. If you're still running stock, I'd go 40:1 and change to a BR7ES plug if you're not running WOT a lot. Just my .02, there's a lot of people in here that know infinitely more than I do.
Seeya