the 80 cc metra will work on your maxi but it is a pretty hard install. you need to bore out your engine case to fit the sleeve into the case and i think you even need to add some more material around the outside so you can form a seal.also, they have an angled exhaust port so youd either need to get a special exhaust or modify one.
you should go with a 70cc airsal or something like that. when going with a kit youll almost always want to upgrade your carb (if you have the bing 12/12 you definatly need to, if you have a bing 14/14, you still should cuz little leaky bings suck.)
also, your gonna wanna get a new pipe. a boss or something like that would work good. youll get a substantial increase with a performance pipe and upjetting even with stock cylinder and carb. just get a new pipe and maybe youl be satisfied and not have to spend mad money and probably fuck up your ride.