These are some pics of the install on my '04 RX-1 (extended) This modification requires a Nytro tank cover, or some customizing of the existing cover. I chose the latter. I removed the stock seat and traced the bottom edge of the tank cover, onto the gas tank with a magic marker. Then I removed the cover and placed the Nytro seat on the sled, and bolted it down. Next I traced the top edge of the seat, onto the tank, and transfered the diff. to the inside of the cover. I ended up taking off about 3-1/4" - 3-1/2" off at the center, tapering down to the edges. I used a dremel with a cut-off wheel, and taped the painted side with masking tape. I also noticed that since I installed the Expert-X, my '04 seat was starting to wear, at the point where the bottom edges of the seat covered the exterior reinforcing brackets. So to protect this $585.00 investment, I had to carefully take a cut-off wheel and a grinder to cut the back-ends of the brackets down. You simply use the tail-light housing and mounting hooks from your '03, '04, '05, '06 (RS), and the seat should come with the pig-tail for the lights, already installed. One other modification that I chose to do was to secure the edges of the vinyl, under the seat, with aluminum tape. It is my hope to prevent any tearing of the fabric from the staples, and to prevent water from getting into the foam. See comments below for the ride quality. IMHO: You can stuff Trophy game, Turkeys, pizza crust, peppers, and even yourself at a good buffet, but you shouldn't have to stuff a snowmobile seat in this day and age (see avatar at left). Yamaha finally got it right.