Thanks man! I'm so excited. I think I'm just going to go with another set of kosei k1 again with tax return. But if I can save enough between now and then, do you think it would be worth getting Advan ad08r or should I just get S drives again?
Unless for some reason you're wanting to stick to the brand, there are equally-to-better performing tires for cheaper than the ad08r's.
Toyo R1r, Dunlop Z2, Bridgestone RE11A, and BFgoodrich Rival are all about $45-$80 cheaper(per set) in a 205/50R15 and are all just as capable performance wise for any aggressive street use or non-competitive autox(some are better, some aren't for all out competition autox. Just car, setup and driver dependent). Yokohama's always tend to be on the expensive side for no real good reason..
As far as comparing the ad08r's to the s.drive, the ad08r's will far out perform the s.drives but they also cost a lot more and will have a much shorter life.