GTPower - What I don't understand is that when I'm not driving the car (In Park, or Neutral) I can rev the engine to 3500 rpm. But when it's in drive, it causes issues and can't get past 2100 rpm. If my exhaust was clogged causing these issues, wouldn't I be limited to around 2100 like I am when I'm driving? Just curious, not trying to argue at all.