Mobil 1 Full Synthetic FTW!!!!!!!!!!!!!
I switched to it at my first oil change and will use nothing else. It costs damn near 8 bucks a bottle but you'll know where your money went the first time you ride.
Could be the placebo effect but my bike felt like it revved faster, clutch and transmission action was a lot smoother and quicker and my gas mileage improved slightly.
They have one kind for v-twins and one for sportbikes, obviously you want sportbike. Mine which is a kinda-sportbike v-twin was hard to judge, I called suzuki and they said use the sportbike as the the revs and internals are pretty racy compared to harley's/cruisers which the v-twin is made for.