First lets establish a goal to have everytime you launch the car. In general, you're going to want to leave the line with as much boost as possible. If this is a new concept, don't be alarmed. You'll see why in a minute.

Contrary to popular belief it doesn't take a GREAT driver to launch this car. To tell you the truth, I don't know the exact rpm the motor is at when I give it the clutch. The reason? Simple, it's different every time :)

Let me tell you, as close as possible, exactly how I launch the car. Before I even get close to the starting line, the motor doesn't see above 1500rpm. I want the clutch to be as cool, and as grabby as possible. When I roll up to the line I do a couple of nuetral revs to increase vacuum (works better to create boost later). On the line, seconds before I launch, I rev the motor between 2.5k and 4k. This is to get my rythm going so that I catch the motor on its uprev (you'll se in a sec.).

Eventually when I engage the clutch, I want to have the turbos pre-spooled so that I'm already making plenty of horsepower. That way when the clutch is engaged, it has the power available to dig itself out of the hole.

I don't slip the clutch, and I don't sidestep the clutch (6k dump). When I do engage the clutch, the motor has been on a free-rev from ~3k to ~5k or more. I usually "aggresively release" the clutch anywhere between 4.5k and 5k. Honestly, working the clutch is the easy part of the whole equation. It's what you do before you drop the clutch that matters.

When the clutch is engaged, the motor hangs around 5k then gets drawn back down to 4k ("hanging revs"), then catches up with the drivetrain, and from then it's all about rowing gears. You can hear this happen in one of my videos:
This is one where "hanging revs" are very audible"
http://streetracing.crosswinds.net/041401/6.asx (please type the web address into your browser. It won't work if I link it. Sorry.

This one is an excellent way to illistrate how I get into a rythm before I launch: http://streetracing.crosswinds.net/051201/17.asx (once again please type into your web browser to make this work)

And this one will illistrate both how the revs "hang" until the driveline catches up, and how I rev the motor to get into my rythm:
http://streetracing.crosswinds.net/071001/5.asx
(sorry, but yet another inconvenience.... typing in the browser)

IMPORTANT: don't just watch the videos, listen to the wagon, and imagine yourself doing it in real life.