Just added the front and rear SumoSprings to my 2014 S. I am a retired lawyer with minimal mechanic experience. If I can do it, anybody can.
A couple of tips for the DIY crowd. The front OEM does not have a 10mm bolt as the Sumo pamphlet states. It is 1/2". You have to put a washer and bolt on the Sumo but cannot get fingers into tight space. Put a dab of caulk on the washer so it sticks to the bolt.
When you try to get the OEM rear bumper stop off you have to pry it off with a screw driver. The driver side came off fairly easily. The muffler side is hard to get at with a long enough screw driver. Use a boxcutter and just cut it off at the front or back metal bracket. Very easy.
You have to force the new SumoSpring into the metal
bracket. Clean the bracket and spray it with silicon spray. It slips in with little effort.
I already had installed the Helwig anti-sway bar and it made a noticeable difference, but the addition of the SumoSprings front and rear make a big difference. When passed by an 18-wheeler the effect is about 10%-15% of what it was. The wiggle caused by following in the rear "wash" of an 18-wheeler is reduced to negligible. SumoSprings are the best $350 mod ever!