Well, I can tell you this for a fact my original 66 383 had an advertised horsepower rating of 325 at 10 to one compression when the engine was tore down at 58,000 miles untouched the Pistons were way farther down in the bore than a ten to one piston would’ve been in fact, the calculation came out to 9.4 to one you can’t argue numbers but the point being by the time that car with that 426 was sent to Mr. norms Tom Hoover himself well before October 1965 was driving around a 66 street hemi four-door Plymouth testing it . There is just no comparison of a red ram 426 street wedge and a 426 street hemi , if it was such an awesome set up why isn’t there more of them out there and people building that engine combination .