Off and on this week as I would pull away from a stop there was a loud roar, like air/exhaust being pushed through some small outlet. It seemed like some sort of wastegate noise. I still have boost. This happens off and on for short periods. And if I press more on the gas while accelerating there is a slight squealling like a slipping fan belt. Does this sound like the wastegate going out of adjustment and actuating ocasionally ? Could this be related to my AC compressor(that hasn't worked for two years) hence the belt squeal? Any thoughts on this mystery roar will be greatly appreciated. Thanks, B Allen