Which part of more HP at lower RPMs makes you think they have larger cams? With 1.6 rockers the Mags had about .60 less lift, no idea if the 5.7s are 1.5, 6, 7, or whatever.
I'm certain the 380hp crate motor has a larger cam then either the 5.7 or 6.4. Pretty sure the stock 5.9 (and 300 hp crate motor) has a smaller cam than the 5.7 truck motor, though. Never meant to imply the 5.9 cam was bigger than the 5.7 cam. Only saying it took a big cam in the Magnum to catch the stock Hemi.
