Sorry, I have no idea what my compression is, but my squish clearance is set at almost the minimum, which would make it a touch higher than stock. Nice bottom end for tight trails and single track. If I was ice racing or supermoto I might want to reduce the compression a touch to help the engine rev out (while keeping the squish clearance at minimum). I am not sure what works best for sand drags (gowen would know). With a powervalve, the compression ratio is dynamic and decreases as the power valve raises the roof of the exhaust port. Cam.