Time to start with mods!

Ok so I got my mostly stock 91 GT running good and all the little kinks worked out. So I'm going to start with the bolt ons now and I'm looking for input on what I should do (in a order sort of), what works, manufacture recomendations and hell maybe prices. Car is a 91 GT with an AOD and it will prodomently be a street car.

Here's what I have so far:
COMPLETE tune up
SN-95 5 lug conversion with Cobra brakes all the way around (not installed yet)
1995 cobra rear diff assembly with LSD and 3.73 gears (not installed yet)
No mufflers

as in exact HP? I dunno wherever my mods take me. I'd like to keep the power band funtioning under 5200RPM. Lots of torque since this will prodomently be a street car. Maybe mid to high 13s....maybe low 13s with a lil nitrous. I'd like to be able to beat N/A Cobras in the occasonal stoplight drag.