Hey guys, the Ryobi 4 stroke I have been working with responded greatly (nearly a 1000rpm increase) when going from 15% to 30% nitro. This pretty much verifies that the comp. ratio is low. In my case adding the nitro is about my only alternative due to engine design.@ 30% it really rocks, idles better, and I find no signs of detonation. Also I runs best on an OS A3 plug.