Well, at 48,000 miles on my 15 RT I decided to change the spark plugs. I am not going into a big HOW TO article here because IdahoMtnSpyder has a very good post with pictures (thank you for that.) I will say the job wasn't as bad as I was anticipating and if these make it 48000 miles I will be ready to try it again or the next guy can do it. The job took a total of four hours that included a break for a sandwich and a refreshing beverage. If you take this job on buy the plug kit from Baja Ron. Not only does it include everything you need, but the price is very good. VERY good! If I were to buy everything individually I not only would have maybe twice the $$ in it, but would also have leftover stuff to store or worse yet toss out. Another tip, the foam insulation above the airbox is breaking down with age and will fall apart easily. I first though about removing it altogether, but mine wasn't totally shot so I kept it in place. I removed and replaced one plug at a time and covered the open hole with a clean shop rag while prepping the new plug for installation. Can Am engineers have managed to get five pounds of crap in a two pound bag so working space is tight. While maintaining these machines isn't as easy as my Moto Guzzi or 400 Burgman most tasks can be performed during a rainy afternoon like I had today.