My 07 Electra Glide Ultra's exhaust pipe has turned yellow all the way back to the muffler on the right side. Is this normal for a 96? My 1985 88 never turned color that far back but I don't know about this 96 that I purchased used in May. I've only ridden highway at 70 mph for 200 mile stints and am getting about 44.5 miles per gallon. Bike seems to be running just fine with no pinging or backfiring. Well until two days ago I got one backfire slowing down once but that's it. Would seem just about normal to me but I'm not sure about how far the yellowing is going. My first thought was a lean tune but only one backfire in three months and absolutely no pinging up to 90mph. That's just the fastest I've gone around anyone so far. I felt like it had more in it if I wanted it. Could the darn thing have "learned" a lean condition. Or should I not be concerned with it and just continue to ride it this way? Whattcha say?