I use to have a XVS 1100a and had changed the rear shock to a Wilber's progressive shock with all the pre load settings you needed and 22 rebound settings dead easy to addjust. then when I got the 1300 with 2 up i have the problem of the exhaust scraping on the road on right hand sharp corners b4 the floorboards, so have started my search for shock, first place it tried was Wilber's and after many tries found out to my disappointment that they don't make a rear shock for this bike :-( but suggested that I go to Hagon shocks and after mush research I have bought one, even they dont list one for the 1300 but they are the only company that apparently makes a progressive shock for the rear of the 1300 (think they keep them out the back under secret bike business) just for those that are interested The model you require is 62097 Hagon Mono Shock , Hagon are the only ones who make this sort shock. Mono Shock, 38mm gold zinc plated steel damper unit fully re-buildable, 18mm piston rod, wide ranging single circuit progressive damping adjustment with automatic compression / rebound balance. Red powder coated spring, fully progressive spring pre-load adjustment. Supplied complete with end mounting bushes / bearings, tools and instructions for spring and damping adjustments. 2-year guarantee. I should have it tomorrow and will add to this post after to let you all know what I think I all so have on order a set of Hagon Progressive Fork Springs to match the rear shock they should be here is a bout 2 weeks and will also add a post here on a review, from what I have read this should also get rid of the clunk in the front end that everyone talks about.
PS Wilbers got back to me after I bought this one and said that (I Live in australia) if I send my Shock to there retailer in South Australia they can send it to Wilder's head factory and they will make one but they havent tested one yet but would make one off mine, hmm so I would guess that I would be with out a bike for more than 6 weeks as it takes 4 weeks to get one of there shockes to start with.