I have 13" shocks on my SuperLow, but I have also corrected the awful sag on the front forks, so it is now a Super-not-so-Low! If you are serious about jacking up the rear end with tall shocks, you really should consider doing something at the front as well.
XL, I have the Progressive 440 standards in the 13.5" length and the top muffler vibrates against the bottom shock bolt on occasion, when unladen, but just barely. Somone posted here a few years ago that the R model, which came equipped with 13.5" shocks had a dent in the mufffler for that reason. I never checked that out though.
I have 13" shocks on my SuperLow, but I have also corrected the awful sag on the front forks, so it is now a Super-not-so-Low! If you are serious about jacking up the rear end with tall shocks, you really should consider doing something at the front as well.
I want to get the roadsters front fork assembly but its like 350.00 each fork leg I am wondering there is any cheaper method?