He won't find much more than the chamber diff in size if he already has 2.02 x heads.
They're 68cc he says. I know they flow at worst 218 cfm peak. Set of mags i flow tested peaked at 204-209 cfm.
How big the mag chamber in comparison might be the final blow. Probably not much diff other than shape. I'd stay with the x heads in this case. The cost/trouble to change over is close to no diff or worse.
