RS5F31V boxes don't seem to be as strong as people make out. Going to PTS RR on friday a couple of times the car jumped out of 5th. As this happened on the same box some 40,000 miles ago it seems that once again 5th syncro has worn. I hoped it was my bent engine mount, but thats replaced now and still does it. So box will have to come off soon for a new gears. Anyway check out what happens when you put 150+ odd bhp through a standard K10 engine mount, and also how reinforced the ST ones are by comparison.
Ed
Ed