I have used PowerTorque for 4 years since first purchasing my HSV Grange in 2008. Shaun at PowerTorque was recommended to me from a member on the LS1 forum. I have no problems recommending the servicing and work I have received there and the servicing costs are far less then the Dealers. I have found Shaun to always give an honest opinion and he has even talked me out of having unnecessary work done, which is very hard to find in mechanics.
Approximate cost: $180