Outdoor Activities - Quad Bikes, GoKarts etc in the Midlands

[R2D2]

Hi All

I'm looking to do something for my birthday in the Midlands area with approx 10-15 people, something outdoors like quad biking, off road karting, go-karting etc. Does anyone have experience of a GOOD place to go, somewhere you get your monies worth. If its quad bikes you're going to suggest then preferably the engine needs to be over 125cc

Answers on a post card - thanks!