Picked up 12 hp with Harland Sharp rockers. Peak hp was at 5850 rpm now it has 512 at 6200 and 509 at 6500. We will be testing the PI intake next.
What rockers did you have on there to begin with, factory stuff? Did you happen to check total lift before and after the change to the Harland Sharps? I've seen a fair number of factory rockers that are not 1.76:1 for the rocker ratio; if the Harland Sharps are a higher ratio than the ones you replaced, your HP increase makes sense.
Your test with the PI intake will be interesting also. During the intake testing for my book I found that at horsepower levels around 425, the factory iron CJ intake clearly outperformed the PI intake. However, as horsepower levels increased, the PI intake started doing better. Contrary to popular belief, the PI intake is not the same as the factory iron CJ intake, in terms of runner design and volume - Jay