Adam, they use the standard 5.0 in the Mustang GT's. Of course, the Cobra's have the 4.6 in them. The cats are removed, an H-pipe installed and the computer reprogrammed. I'm sure they will still have a few left by Dec. 1st. Ask for Ken Thom. He is in charge of the place and handles all the sales of these cars.I am planning on taking the 3-day course but haven't set a date yet. They are great people to deal with. Bob even autographed my dashboard!