First off are you sure it's a 400? Second, if you can burn rubber you probably have more hp than that. Can you post the dyno sheet? Was it a Mustang dyno? What as the torque number? The first 400 I had run was stock with a little cam and it came in at 298hp/360tq@5000ft elevation on a dynojet machine. Should be about average numbers. Best I could get out of it was 14.4 in the 1/4. You won't get as good of numbers from a Mustang as you will from a dynojet.