a good lawn and garden shop should carry it. to save some time, just call Opti2 direct and they'll find the closest dealers in your area. they're real friendly folks.
blakenstien, i wasn't making an attack on you, just explaining things my way.
i don't know the manufacturers of your motor, but i do know this; almost every single manufacturer of every single thing in the world has a disclaimer that reads "warranty void if altered, abused, used for racing, modified, etc etc etc..."
it's a CYA for them against the average consumer.
besides my opinion and experience with Opti2, everyone is free to make their own choices. no one's gonna force you to try it. if you don't like it, don't use it, simple as that. as long as your bike's running and you're having fun, just leave it at that.