I'd like to know too, sometimes my car hits hard and then completely goes flat on power. Like BUTTSURGE then flat Corsica-like acceleration all the way through 5500 rpm, where peak power should be (in third gear). I suspect its boost leak. If I lift and then re-apply throttle, the power comes back and it surges to life again. Sometimes I have to merge on the highway lifting and reapplying throttle every 1000 rpm to get the adequate snort that I expect. I'm not sure how I could possibly prove this to a dealer without them thinking I'm totally full of it.