This particular 2006 ST1300 is my third. I bought it in May 2016 with 5700 miles on it. I have put about 3K miles on it so far this summer. I noticed today that the left side rear portion of the exhaust system is changing colors as if being really hot. However the right side of the bike suffers no discoloration. Would you think that the left side might be running too lean and overheating? I have not looked into the throttle body setup to know if it is even possible to have differences in that way. I know the bike runs like a scared rabbit and gets an average of 42MPG per tank. Should I be concerned enough to have it checked out?