Put doubles on my 335 JD tractor today. Sounds like a helicopter, cuts much better, slings clippings like crazy. Only one problem, it does cause some blow-out at the front of the deck, not bad now, but when it gets dry and dusty I may have to go back to singles. The doubles don't seem to bother the 20hp. Kawi. 54' deck at all. As soon as my m665 needs the blades sharpened I'm gonna put'em on it too.