Hi Z fans.
I just wanted to relate that recently I traded my planted seat rails for the Z1 seat rail mounts. It was well worth the effort in my view. The side mounts by Z1, see Link:
Z1 Seat Rails for the 370, are superior in the fact that the side mount seat rails mount lower in the car to start with and are alot less of a fuss to setup. You should buy at least one hardware kit when you pickup your rails. It'll be good enough for both sides of the car. I first swapped out my factory seats for Sparco Evo XL QRT seats and tried to make the Planted mounts work along with the Sparco side mounts. This forces the seatbase to start out 1.5" to 2" higher on both sides of the cabin. If you use a slider, even more. Well if you track your car like I do then every inch of headroom is precious. Swapping to the Z1 seat rails gives you back the room you need on both sides of the car for adequate helmet clearance be it a passenger or DE instructor.
The passenger seat mounted with Planted Seat Rails, sliders and Sparco side mounts.
Same seat on Z1 Seat rails.
Sorry for the sideways view of the second image. But the real indication of success is the lower front right part of the seat. It sits quite a bit lower with only one seat mount needed instead of two or three.
PM me if you have questions or want to see other images. I'll take more pictures if you need me to.
NOTE: The hardware spacer count on the door side rear mount is key. You only need them in this one location on each side of the car, no other location requires them. One larger inside and one medium outside the Z1 rail. But only in that location on each side of the car.