In my owners manual it suggests a good mile or two on the highway after stop and go traffic to clean out deposits. So your theory is correct that high revs clean out deposits. As for 200-300K?? I doubt you'll reach that high of a mileage constantly free revving. Once and a while its good for your car...constantly will decrease your engine life. If you keep up on maintaince then you should get to 200K, but who knows..im just appling some common sense.. BTW-do you have a pic of your car w/ the contours???