>I can't think they can go much quicker. On some of the straighter sections they exceed 200mph on effectively a relatively narrow country road. I used to ride big bikes and I remember how fast even 80 mph felt on roads that size.

Ah bikes.
This is one of our bikes

http://www.mijnalbum.be/Foto-ZVIVBXMB&album

Honda 1000cc Fireblade. A oldie but still going strong...