I contacted them today and here is the response I received from tech support
1: The rear spacers are made from a composite glass filled nylon material.
2: We found that on the newer Trailhawks that the newer model years actually limited the down travel on the A arms with them making contact the bottom of the engine cradle/subframe, making it nearly impossible to get the front strut spacers into place. Our kit does in fact fit the new Trailhawks, but the installation is tricky and the performance with the limited front down travel issue, so it wasn't ideal enough to recommend it.
3: We found the rear wheel centering wasn't enough to interfere with proper suspension geometry in our testing, so we left it as is to retain as many OEM parts as possible.
Though I currently run Dobinson plus lift on my 2017, this seems like a decent set up and the price is so attractive vs the alternatives.
Now we just need a Guinea Pig to do an install