not much over 550. Maybe 580 at the most.. Its an older 302 block. Not a 5.0 block. Its a 69 block. Come out of a Mercury Couger. And those two guys i know, i just got off the phone with one of them, he said he had the Street Fighter kit. He told me he has 90 passes on the motor and its got 46,000 miles on it and uses hardly any oil and is holding together fine. its set at the factory rev limiter of 6,250 and he shifts at 6k. He's only got an E cam and Edelbroke RPM's and a P1SC Pro Charger on it. but i dont recall how much boost.