I just installed the 88a version on my 2017. I wasn't sure how much of a difference to expect since the 2016+ has a stiffer stock RMM (I noticed the stock RMM had a label stuck on with "ST" on it.) But the difference was huge. I remember when I test drove the FiST for the first time, I thought the launch and shifts felt very lurchy. I thought it was just that I was out of practice with a manual (I had been shifting on a 92 hilux pickup, and a 1954 Willys CJ3B.) But, as I continued to drive I never seemed to get any better at it, if I wanted to launch quickly I could expect the car to jerk a little bit at launch and between 1 and 2. This mod pretty much eliminated that. It also felt like the handling improved, less torque steer or something. The vibrations are very noticeable on a cold start at idle, but once it warms up it is minimal. I kind of like the vibration though, I feel more connected and I feel like I can feel the power and the engine a little more. I will say it does seem slightly noisier in the cabin, I'm not sure why because it doesn't seem like vibration noise, just more engine noise (I still have the symposer intact.) I'm looking forward to seeing if it mellows out. Just my two cents...
I torqued the two bolts through the bushings to 50 lb-ft (I ramped up to 50 lb-ft because I had read about others stripping threads), and the other nuts to 20 lb-ft. I put anti-seize grease on everything (maybe should have used loctite). I figure I will check the torque on the bolts when I get my springs and dampers installed next. Overall the install was easy, I did it with my wife and kid hanging around outside, no cussing involved. I am glad for this forum though, otherwise I would have had no clue.
My ramps wouldn't work so I jacked up the car with a 3 ton hydraulic jack starting with the drivers side. I set jackstands at the jacking points. I used foam padding on all the stands and jacks. I decided I didn't fully trust the jack stands, and put the ramps under the front tires. At this height the rear tire was completely off the ground too, which surprised me and kind of sketched me out. I then moved to the passenger and did the same thing. I had chocks on the rear wheels also.