One on the Bay at present the same as Paul Craig and me use.
http://www.ebay.co.uk/itm/Drift-X170...item3a7f87efa7 Its new and £26 at present. Not supported now as the company do an HD range but its good enough.
You have to jump through a few hoops securely fitted, permission from clerk of course and installed at scrute and signed by scrute then return form to C of C.
Look on Youtube for Ghostie749 and you will see the quality of it.
Threaded Mode