I dunno about the 600s. I keep the busa about 4000-4500, just below the threshold where the power really kicks in, and high enough to get the bike rolling w/o bogging at the rate I normally release the clutch. Then roll on the throttle at launch while I let off the clutch at a rate you can only gauge being on the bike. It's practice, I know what it feels like if I'm too quick releasing the clutch-- *it'll bog because I didn't have enough throttle and let the RPMs drop *it'll spin the tire because I didn't put enough heat in it or picked a bad launch spot on the track, or *it'll snap up into a wheelie, instead of just carrying the tire like a plane taking off and landing again which is what a good launch will feel like on the busa. The only way you figure out what a good launch is, is by checking your 60' times and remembering how it felt. If you're too slow releasing the clutch lever, you'll take off, it'll just be slow and affect your 60' time. On your 600... I'm guessing you'll probably want to start the launch in the 6500-7000 RPM range and start tweaking from there. But, I've never been on a 600, so I don't know where the engine feels the happiest... it's usually a little less than half the redline as my rule of thumb. Assuming it's not a drag bike with a 2step / RPM chip and extended wheelbase/wheelie bars. Those are different animals.