Best bang for your money is a stock shock with a progressive spring this is what I would do buy a second hand newer model stock rear shock and install the progressive spring on it then install the completed rear shock at your leisure I tried a complete TRAXXION rear shock once a long time ago and it blew a oil seal in only like 20K or so but that was a old model and I believe now they have improved the new model shock ? good luck
I agree with the goldwing fan, what I did was to purchase a 2012+ and later stock rear shock (on-line Ebay) and had "RaceTech Suspension" in (Corona, ca.) install a new heavier rated spring and install a braided line between the pre-load adjuster pump and ring (it won't swell like the OEM's do). (I did not want the shock rebuilt)
The Ride is AWESOME now for me and the misses now.
Just check into the aftermarket Spring you want to use.