Mustangs are cheap, can be made to handle great, and retarded amounts of power can be had for cheap. I had a 91 hatch with a mildly built 306, nice suspension, and a bolt in cage for 2 years. It was a rock solid track car, made 355whp on 87 octane, and took non-stop abuse. Subies are great, but a little sloppy on the track. A fox with bolt ons and slicks will kill anything but an STi.