Did this last year with Brownie and a few of his mates. Was a good track/loop but like Brownie says DON'T go with an MT43 on the back, it was cr*p for traction in the damp and slippery conditions but A) not knowing any tyre was allowed and B) not having a spare rear, i didn't have much choice!
Well worth a trip IMHO and the KTRC guys are most hospitable and friendly.