I have a 2002 Softail. About 2 years ago I had a 95 build with Andrews 37 cams installed. I believe the compression was 9.5/1. I had de-compression valves installed to ease starting when the engine was hot When I was in Sturgis area in June, I never had to use the de-compression valves The engine fired right off with no grunting. (even in the 100 degree days they were having and even if engine was still hot) Back home in Illinois I need to use them to keep the starter from grunting when I go to start the engine. Is this due to the altitude in Sturgis and why would that cause the engine to turn over with little effort?