One thing i have found with this head is it responds very well to compression increases. I know most engines increase performance with more compression, but this 511 responded way better than i would have guessed. I gained 4 mph and 3.5ths in quarter in a 3400# A body. Went from a 10.40@130 to a 10.06@134. There were several changes, so not real apples to oranges, but thought the compression increase from 11.25 to 12.5 was big. I also ported the plenum of the Indy 400-3 and added an electric water pump. I'm now thinking about bumping it up to 13:1 on next freshening. This head likes compression in a big way, I think it might be giving it a boost to lazy air flow.
