hi I'm seriously thinking of buying a bumble bee bolt on. i have a china girl mid frame kit at the moment and it does 46 kph its a xbox 66cc. I'm always having the usual problems with these engines. does any one here own or have had a bumblebee kit? how fast are thy? are they reliable. is hill climbing any good (to an extent ) i at least have to go 40 kph? and does the roller slip at all act. any comments or pros/coms are appreciated thanks