You also have to factor in the value of the increased gains vs. the diminishing thickness to your wallet for fuel. If you plan to race a lot, factor in the cost of these expensive higher octane slower burning fuels needed to support that extra compression. Going higher than what the average 110 octane fuel will support (13.0:1 or so with aluminum heads) will add 25-30% or more to your fuel budget which is constant and not a one-time expense like the initial build.