Well... DYNO!

[420nitro]

The thing is this,.. I dont believe it made 290 horespower,...PERIOD!!!!!
Your car, if I had to guess, I would hope for some where in the neighborhood of 250-300 horsepower at the wheels. In your car if it weighes about 2500 pounds like you say,..it should go mid 11's. That's if it hooked! In a normal Mustang that weighed 3300 pounds that made 290 horsepower at the wheels should go mid-low 12's, set up correctley! (on a dynojet 248)
Now you can beat yourself up all day and night, but your not going to know untill your at the dyno shop or track. REMEBER ONE THING AND ONE THING ONLY, DYNO NUMBERES ARE FOR SHOW, WHILE THE TRACK IS FOR THE DOUGH!