I would get the relocation brackets on and change the rear springs if needed to run the taller tires. With the relocation brackets the car shouldn't squat as much since you will be changing the instant center which should make the rear seperate from the body on launch.

I would then work on trying to find some of the power that seems to be missing. Get the car to leave hard enough that it spins and then work with the suspension. I know how to make these cars hook on drag radials.

The launch pic of the car dosen't look too bad.

i have 28's in the rear on my car and i use the stock rs springs on mine. i put spacers on top of the coil springs so i didnt change spring rates, best i haev cut on teh juice was a 1.461 (launching on a 200 shot). I had air bags and they were a pain in the ***. I have all spohn suspension pieces and the lca's