i think 1977 sells them. just think about it like this. any assclown can buy a polini or metrakit, slap it on and go 50 right? you have a tomos that does 55 i think.
but if you use 50ccs, go with a big carb, nice exhaust and fine tuning you can really show off your tuning skills.
big bore kits are soooooo last year =P