Listen to blw's advice. Don't worry about the owners manual and what it says; PR/Marketing lemmings write them and obviously get it wrong. Try a hot plug in it, you might be surprised how much better it runs. I like McCoy 4C and 59 plugs, fox miracle, and Enya #3's. I use a McCoy MC4C plug in my Jett .35 even though Jett specifies Merlin plugs. The Jett runs great on the mc4c.