@Ghinzani, noticing your location in the South West, you should give Wiscombe Park at Colyton, near Exeter, a crack..... Mind you, its a venue that requires huge amounts of 'testicular fortitude' if you are fully committed enough to do a quick time.
The size of the 'accoutrements' required to do an on the limit run in anything resembling a kart would need a strengthened chassis to take the weight of the neccessary sized 'mansbits' to be honest.
It is also an excellent venue to spectate as well.
An onboard clip of Wiscombe
As you will have seen in that clip, it is the last place you want to be venturing from the black bit in anything, let alone a kart. Bordering the track there are some very solid banks, trees and other very unforgiving areas that you will encounter, and the speeds are deceptively fast. .
As Rob Turnbull found out a few years ago
with this big accident at the hairpin
This is just a few seconds of Robs crash from another angle and
really highlights the speed. Quite scary actually. Other than being a bit winded and shocked, Rob was totally unhurt by the way.
Mind you even Gurston has some places you really dont want to go off. Imagine the off in the following clip if you did not have a carbon fibre survival cell, and were in your chosen relatively unprotected kart. This is in the wet and at a much lower speed than would normally be the case in the dry.
http://www.youtube.com/watch?v=mFKZzpVFjBE
I wrote elsewhere on the forum of when I had a huge scare on that bend, thanks to an over zealous scrutineer
when my throttle jammed open but I chose the escape road rather than trying to make the turn.