I rode these things when i was younger,you can get headkits,big bore kits,big bore carbs,exhaust,intake and velocity stacks,spark plugs,lightened flywheels,msd idnition,timing keys,and nitrous,but its only like a 1hp-3hp,if that,they had 2 engines on Go-PED copyrighted models,g23lh and g230rc,the rc was the better motor putting out 19,500 rpms with no weight,and the gearing was changed by the spindle you had.no one has made more than like 5hp,maybe 6...and not many people have hit more than 40+ miles an hour,so all you people are bullshitters,i know all about this.I had like 2 grand into one,Ask OneReving7..he knows