The 5.7 heads that I have are a one off design. I welded up the chamber's and then milled them .025". Custom Ferrea 2.08" int/1.62 valve's with .308" valve stem diameter, custom bronze valve guides and hand ported personally. Exhaust to intake ratio's at mid lift are in the mid to upper 70's with port velocities at 345 fps. Won't see those type of #'s with either the 6.1, Eagle or Apache head's ported or not. BES must have came up with the same conclusion that I had.