Im in the process of getting a upright I honestly think there cheaper then go karts if you dont put one on its top... I use to race go karts in early 2000's. The flatheads cost about as much as a 1000cc engine and you need to pack valves every 3 races max to get the right float out of the valves ($60) a pop... pay out $90 to win for 30 some karts in class... crazy!... Wka rules has killed that whole deal, then people went to clones to cut cost but now wka got there fingers in it now you cant get anything out of a go kart at least around here anymore.. Problem is you have to draw the line somewhere to get the little guy in I like the idea of gas not only does it cut down on up front cost but the headache of flushing the lines every race... yea helps with heat but i hear about people building up engines to get the edge at least in the AMSA and feel its going to turn out like the wka keep them stock and stop making it harder on the little guy. they need a national organization for rules so if people from Indiana or where ever they race other uprights can race in other states and don't have to change anything.. they need to tech more at tracks or a buy program which would i feel put a stop to it..