I have to chime in here now. The most important thing you can do when trying to figure the octane your engine will need (no mater stock or modified) is to know what your cranking compression is. If you have around 175 LBs you can tune it to run on 93 octane or below (Jim Hand and Cliff Ruggles both run their high compression 455 daily drivers on 87 octane and run at the track in the 11's) If you have around 210 compression it will probably need 98 octane to perform the best.

There are a several ways to get to the 175 range. Dished pistons, cam overlap,larger heads.

I have high compression heads (16s) 0-deck block, crower 60916 cam,1.65 rockers, forged pistons. I have around 419 HP and run on 93 octane with no problems at all.

We should all post are cranking compression and what octane we need to run?