FWIW, I did upgrade only my heads, out of necessity. Cracked one a few years back, posted the whole ordeal on here. Still running old school 4 blade prop, original intake. Didn't have the cash to upgrade either when doing the heads, plus I was curious to see what the increase would be for heads alone. Found some GT40 heads in a junkyard for cheap, got them cleaned up and installed, and gained about 4-5 mph of top end speed. Boat has quite a bit more oomph. Not sure how much HP, but it has to be significant to gain 4-5 mph. Had to re-calibrate all the pefect pass slalom speeds in the course, as expected. I do agree that prop changes can be significant as well, and if I ever get the cash, or have a need for more speed, that will be my next upgrade.
Last edited by Kevin 89MC; 12-10-2012 at 04:46 PM.