Suspension Setup

I'd say start with som FRPP C springs, get the Lakewood Traction bars (lower control arms) I like the D&D upper or the lakewood boxed uppers they both work great. Replace your upper control arm bushings too when you swap control arms. spericals are ok if you do more track time than road, I'd stay with the stock rubber though they work great.

you'll want some good shocks, tocico's or bilstien coilovers would be your best bet.
then maybe look into a panhard bar down the road.

I've got about 400hp to the ground and I run C springs, KYB shocks, Lakewood uppers, and Traction bars on the bottom and my car grips great going straight and in the turns it keeps the power on the road. one of my buddy's has the D&D uppers & lowers and his car is all over the place when he corners and the car doesn't get good launching traction either.

Look into the steeda setup, it's designed for mustangs and is a proven combination for street, track, and strip. They've got a stage 1, stage 2 and stage 3 setup. I've got the full stage 3 setup and I've never looked back.