Hard core tuning

hi all, i’m a tuned classic scooter owner, but am sorely tempted by auto’s for the value and potenial performance and handleing, don’t know much about what engines are in what scooters?? second hand MBK nitro 100’s seem to go for cheap. I reckon that this is because they’re air cooled and therefore have limited tuning potential?? am i right? whats the maximum hp i could expect from this motor with extreem tuning?? i was thinking about picking a nitro up and putting a runner motor in it? has anyone done this?? can anyone recommend a good value scooter model with plenty of scope for tuning?

sorry for my rambling post,

cheers, ozzy