I've been twice. They have stock *and* super-charged tillers. Some of them go over 20 mph.
It's a 200 ft course, and the record is about 6 seconds. The tillers sometimes drag the drivers behind.
https://www.youtube.com/watch?v=Kq6GbuVgDZg
https://www.youtube.com/watch?v=0_9mfF0Y2Nc
https://www.youtube.com/watch?v=mMICRlQGsGE
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