I don't go by Horsepower Gain or Loss.
I go by % Gain or Loss.
Usually the 'standard rule' is a 4% Power Gain by increasing Compression
by 1.0 in an Engine with an approximate 9.5-1 Compression-Ratio.
A .50 {half-point} loss in Compression, will probably effect Horsepower by
3% {at maximum}.
