Just Mopar Joe is awesome and so is his channel. But why any doubt when aftermarket heads were used? The bigger valve better flowing heads are what takes Mopars to the next level. In the old days we ported or paid to have our heads ported- or we ran them as is because the aftermarket didn't recognize Mopars. Nothing being taken away from Joe- but with good quality aftermarket heads and a wise camshaft choice I am not surprised at all with his output. Now if he had used unported 906 346 or 452 heads I would say no way.