I wanting someone who has accsess to a dyno to test a few spark plugs for the raptor to see if theres any power gain. The NGK CR10EK part #2360 adds 12hp to yamaha Apex sleds. Dyno proven. It has a duel ground which leaves the bottom of the plug open. Try these plugs. NGK CR8EK (3478), NGK CR9EK (4548), and NGK CR10EK (2360). I belive the Apex is supposed to have one step hotter plug, so going colder might work with these plugs.