I would be very carefull about tapping the camchain tensioner body out to 8mm as the body is not very strong, its only made from thin cast alloy and a fair amount of pressure is excerted throught the tensoiner body from the camchain at high rpm, these bodys have been known to crack with the 6mm bolt and drilling out the body to use an 8mm bolt will only make these weak part more vunerable to failure, loo at how thick the body is on a manual billet tensoiner, and being billet it is much stronger than cast. Using a stronger spring will increase tensoin on the camchain, accelerating wear on the camchain tensioner wheels, and risk breaking the guide at the front of the block held in with the cross head screw. Tension on the camchain will also increase friction within the drive train and so rob horsepower. Fitting a billet manual tensoiner is the obvous answer, prolonging the life of the camchain tensoiner wheels (which are over ?300 to replace!!

), and reducing pressure on the camchain while being unable to back of or break. Steve