I powershift my T5 on the street, never had the Mustang to the track, but I will there too. Luckily, my Dad is a Ford mechanic so he can fix my misses .
I dont see how i could do it. I shift at about 6,000rpm my limiter is at 6,200rpm if i have tried it but i always bang the limiter when i hit the clutch, and my E.T.s go way off. I dont really see the point as long as you shift fast and hard you will run good E.T.s!!
i always powershift it at the track. once in a while i just rip it back into fourth and don't even use the clutch. i'm just waiting for the day my tranny explodes.