I went with the ST springs and added their "Bling Bling" aluminum cross over adjuster.. after a coupler of hundred miles here is my take.. First of all, I can't complain on the customer service thought they great job and the product arrived as on time as described.. second, the suggested initial preload setting was not even close, the bling ring adjuster was not milled correct so once on and tight you could still spin it on the shock.. required me to take a file and open up the end gap to crush enough to lock down.. the set screws are small and a real PITA to adjust once on the shock and near impossible once on the vehicle.. the Oring really didn't stop any contact knock noise maybe just changed the tone some.. I regret adding the ST cross over rings and should I ever have the springs off again they will go away..
as for the springs.. After some cranking down on the settings more than I expected to even get close to the OEM ride height. On the the first ride out felt over sprung and reset my shocks to second to softest setting helped.. but over all the springs eliminating the bottom out and carried the weight and smoothed things out with considerable improvement over the stock..
To conclude.. couple of hundred miles later the springs have sagged more that expected.. but I think the ride has actually improved..
So as for the different spring options out there.. like Eibach
PRO-UTV - Stage 3 Performance Spring System (Set of 8 Springs) By: Eibach and others that don't offer a advertised a to the pound custom spring rate.. I really have my doubts that the Spring rates on ST's are really that fine tuned IMHO... the other spring choices may even be made of a better material that don't sag out as much.. Who knows?