You are going to see a sweet difference Kevin. Does the shop have a Dyno? Would be interesting to see the B4 and after numbers... If you want an educated guess, I'm in at:
Baseline: 372hp/381tq
Mods and Tuned: 422hp/430tq
Rear wheels of course and your altitude taken into consideration. Those are DynoJet guesses....A Mustang dyno will be somewhat higher.