The best I can tell, my stock seat on my 09 RKC is about 17in wide, according to my measurements. Im interested in a solo seat, but when reading Mustangs catalog, it says that the "New" 17in Mustang solo sits the rider 1.25 inches further back and lower to the ground. I don't mind lower, but further back is an absolute NO GO, since I'm already lurching forward and down for the handlebars. BTW I'm about 5'10 and the handlebars seem too far forward and way too low, right now. But Mustang also offers a 15in seat, and it says nothing about moving the rider back. I don't know why the 17in wide would put you further back but the 15in wide wouldn't. Anyone have any experience with them?

 

I cannot offer any advice however I myself am looking at the Mustang 15" Solo. Browsing around I have not seen this in their item description. I would also like to know.

 

You should seriously consider swapping out the handlebars; those stock RK bars are not good unless you have really long arms! Think you can go with the original Heritage bar and still retain stock cables/lines, and the improvement is waayy worth it. I'm your height, have had 2 RK's, and different bar was the first thing changed on both of them. Then, you will probably be OK with the Mustang 17" Solo.

 

but found it far too hard for my liking. With Mustang, the wider the seat, the farther back you sit. I sent mine back after sitting on it only once but found it to be almost the same as stock and about 1" lower. The 15" didn't look or fit quite right on my 09 RK but that might just be me. If you want to get closer to the bars you have a few choices. First is the HD Sundowner. It sits you about 2" closer than stock and sits you lower too. Or, you could put a new set of taller/pullback bars. I put the Heritage bars on mine and the effect was immediate. 2.5" higher, 2"narrower and less of an angle for the grips.

 

http://home.comcast.net/~kceder/seats/seats.html

I have played around with some mustang's recently. I have the 15" solo as well as the super touring seat. The Super touring seat runs about the same profile as the 17" solo. It is just wider. I does move you down and back. The solo 15 is also a lower but not quite as far back as the newer seats.