I've always launched around 4.5k-5k rpm. Slip it just enough to catch and then floor it almost at the same time and let the clutch fully grab. It worked for me on my ACT 2100, but not so well on my ACT 2600. Maybe I'll try dumping at 6k once and see how that goes. I bogged when I tried dumping at 5.5k though

. My car must just be too weak, eh?