I just installed the Sundowner specifically for the RKC. However I have only put on about 10 miles on the seat, but I can tell you it´s a hell of a lot more comfortable then the stock seat. My only concern is the detachable backrest I got with the bike. I didn´t spend a lot of time trying to get it on, but the pillion is wide and I think it´s going to be a very tight fit.