[09CTSV]

This is my second supercharged vehicle, I've had two other turbo's as well. My 09 V ran pretty good and the exhaust was a typical GM style which turns black on the chrome tips from the carbon. The two turbo's did this but like the 09 V the exhaust itself was clean, you never saw any heavy black smoke when being aggressive with the throttle.
This 17 V could kill a swarm of birds on take off. I never noticed it till this summer. Someone commented I was leaving a lot of tire smoke when I took off. The back of the car is covered in soot after a day or two of driving it. The stealership, my favorite one, said everything looks good in the fuel trends. I think I've got an injector or a few leaking down and causing the black exhaust. When I start the car it is clear, smells different than when new but not black exhaust or a heavy rich smell. When you step into it or even gently roll into it the exhaust is heavy black smoke. After about two or three times it clears up for the most part. I've take the car well above the legal speed limit and the exhaust was clear.
Anyone with a supercharger have any similar experiences? I'm tired of the crappy GM dealers and don't trust them as far as I can piss.