What should i do next????

Ok, is this 01 GT you're going to be getting an automatic or 5spd. Second, so you don't get flamed, Steeda doesnt make gears for Mustangs. They sell Ford racing gear sets.

As for the gear ratio, 4.30's are great for a naturally aspirated application. However, for a boosted application, you might want to step it down a bit. If you're going to have an automatic, I'de go with 4.10's with that supercharger but only if you plan on running a taller tire on the rear, like a 28in DR or slick. If you're going with a five speed, I'de get 3.73's instead for a blower application.

The springs should help with the way the car handles but when you say "competiton springs", do you mean drag race springs or road race springs ?

The bassani X-pipe will be good no matter what so no problems there and the same applies to the cat-back and K&N air filter.

As for the chip, have you already bought this ? I wouldn't buy a chip until after I knew what mods I was going to do and I would probably go with Superchips Tuning, not autologic but thats just me.

How about a new intake plenum such as the C&L or Accufab ones. Subframe connectors and lower control arms if you are planning on drag racing any. And as stated above, the 4.30's are a little steep for a boosted application so you might want to reconsider that. And how about a little bit of spray? Cheap horsepower...

In that case, get some u/d pullies, plenum, suspension work, and sticky tires.