Would like to know how many of you have pretty much spotless exhaust tips on the inner rim after let's say 2-3 weeks of driving, vs black carbon buildup after 2 - 3 weeks of driving. I currently have almost no carbon buildup after two to three weeks of driving. What's weird, is I remember periods of time in the past where I would have carbon build-up after 4 days. Something has definitely changed. Car is running amazing. Hoping I am not too lean.