I was pretty happy with it(and so was the customer), and the on track performance spoke for itself.
I don't think I'd feel good about recommending 572-13 heads to this customer and then have him only pick up 50 hp. If this customer switches to 572-13 heads down the road then I'd want to see over 1000 hp.
Respectfuuly, if you can explain how these '900hp' 325cc EZ-1 low -port heads are better than a 345cc -1 then it would be easy to explain how an equally prepped set of 572-13 heads would pick up OVER 50HP. There are a few examples of 572-13 headed motors that make over 1000HP. At least one I know of came from your last engine builder! 8.6's @ 3350 on a 10.5 tire about 15 years ago. Beyond the added flow and cross-section just like you have mentioned the improved valvetrain allows 'more cam'.
