twin turbo questions

ok, ive decided I want tt. my goal is to make a sleeper with 600+hp/600+tq @ 10psi. i want a kit capable of 15psi tho. the kits im considering are HP and Hellion.
1. Which kit would be the best (price vs goals).
2. Can those goals be reached with stock heads/intake (p&p of course)?
3. What cam is recomended?
4. Whats the smallest turbos that will produce the 15psi?
5. What kind of tranny (automatic) upgrades?
6. Which kit can I run cats with?
7. Muffler and exhaust piping suguestions? im looking for a sound that is as close to stock as i can get
8. Can the suspenision offered with these kits be upgraded to air ride?
9. Which rear suspenison would be best to go along with the needed front upgrade?
I have a 1996 GT with a automatic and i do believe it has PI heads/intake, have yet to take the vavle cover off and check for the stamp