I basically didnt do my homework!! I just rebuilt my engine(f54 block p79 head) and it worked great! I'm currently running it with triples, headers & ignition. I recently came across a P90 head thinking i would create more hp, but ended up slower then my last setup. I had the head rebuilt, matched ported & polished the intake & exhaust. I was thinking it was a installation error so i did a leak down test & compression test. I found no leaks but I only had 120 psi across the board!! I have a F54 block with stock flat top pistons. I'm pretty sure i'm running the wrong setup. what head should i use to get the most power? sorry , i forgot to mention i'm running a stage 3 cam from motorsports. I was looking around and i saw E88 & E31. Is this correct?