Starts on a 450

Have you thought about one of those "Holeshot" fork devices? They work by compressing your fork, and holding it down in the stroke. Prevents wheelying off the start, and more tractible power delivery. Then when you compress the fork in the first turn it releases, and the rest of the moto is normal. I'm sure everyone's seen these by now. They retail for $80 and up, depending on brand.
Here's a Works Connection one for your bike: www.worksconnection.com/store/product.html?prod_id=1119

2nd gear, pin the throttle, slip the clutch as fast as you can while keeping the front wheel near or on the ground.

How much do you weigh? You might even try 3rd gear.

The races I've done indoors had so much traction that keeping the front wheel on the ground is the biggest problem. I've never raced the 450 indoors, but I used to use 1st for starts indoors on the 250. Taking off in 2nd would have me still slipping the clutch all the way into the first turn and took much more concentration and effort than using 1st. I still never ran out of first gear on the way to the first turn and had much better success than using higher gears.

Indoors I found myself usin 1st and 2nd rather than the 2nd and 3rd I use most of the time outdoors.

You might not get a chance to practice the start before the race, but you can stop after coming out of a turn and try a start in the middle of the track (if traffic allows) to get an idea of how it will hookup and how much throttle and clutch you need to use.

that must be one tight track to be using first during the race. Ive raced 2 different style supercross tracks and can't even imagine using first for any of it especially on starts and I'm a big guy too.

I've only done one "real" SX track (Atlanta SX in Georgia Dome) and that one was faster...2nd and 3rd. The Ultracross, Arenacross, and local indoor races (read: Ag center after the cows are trotted out) were much tighter with shorter starts.

The thing about coming out of a tight turn indoors in 1st is that you are pretty much guaranteed traction and you come out of the turn on the pipe instead of trying to slip the clutch. I always had to shift to 2nd for the jumps, but really liked 1st out of tight turns.

Me outweighing the bike might have something to do with it, too. I consider it an advantage that I can flop my belly over the bars for traction control and steering damping. :confused: