A little different yes but that's way out. Keep in mind this is a Mustang Dyno not a DynoJet, it typically loads the cars and reads 10% low. On a DynoJet this would be over 300 RWHP and I've never seen any 3 or 4 valve car over 300 RWHP without a mid-pipe, mufflers, and a good tune. I'd say...