The Progressive full length springs do indeed use the stock spacer. They are a very worthwhile upgrade. Buy them from Fast Eddy & be happy!
What preload setting are your stock shocks currently set on? Anything less than 3 is too little preload for 2-up. And anything more than 3 is too little damping...
I have Progressive 412 standard length (12.5") heavy duty shocks on my 07 SM, however I normally ride solo. I weigh about 170 without the riding gear, however the bike has extra weight from a number of accessories (lightbar, flyscreen, footboards, centerstand, Tsukayu hardbags...). The 412's are currently set on preload setting 3, which may be too much. I'll give setting 2 a try & see how it does.
