Ah, ok... I've spoken to Eddy now and he said that the top gear on his 6 speed isn't too much different to the normal 5 speed box. He changed his because Skoda decided to make the gear ratios in the 4x4 5 speed box optimised for off road use :(
He suggested raising the rev limit, but also mentioned that there is a kit for the 6 speed box that will give 202mph at 7k rpm :)
http://www.hpamotorsports.com/product_drivetrain_gears.htmBumshanka
If you've got decent internals, then you should be able to rev the fucker to 8k...
Fast enough for you?
That link also has max speeds for the standard 6 speed box.... Apparently 8k would give 192mph if the engine could pull it.
Looks like a standard 6spd would give you a little more speed even with a 7k limiter, but even a basic remap should have a 7.2k limiter which would allow 173mph.
Anyway, thanks to EddyH for all the above info!