after looking at the cost it will cost me about 840 for a set of new ford racing PI heads... i figure i would do that over buying a used pair($300) and then sending to the machine shop as it wont be that big of a price difference....but then i saw these.

Patriot Performance 1004R - Patriot Performance Ford Stage II Remanufactured SOHC Cylinder Heads - Overview - SummitRacing.com

thats supposed to be 40 HP over the stock pi heads? giving me about 80-90 overall. thinking of pennying up the extra cash to do that....or is my logic off or something im missing?