Even at 23,000rpm, pitch speed of a 5" pitch prop is only a bit over 108mph. Little airplanes are very deceiving when it comes to speed. It sure doesn't make them any less fun, though. Here's my Screamin' Demon with a 32SX, Macs pipe and APC 8-7 prop. Static rpm is 18,000+rpm. It's in the 130mph range with GPS telemetry data. Looks like my Bearcat will get a 32SX. I've got 7 of the little jewels.

https://www.youtube.com/watch?v=pa0jmNXeMU8