I would also opt for a different route if I had to do it again. Most people I think run the pro-kit but I am unhappy with the progressive springs. I have the adjustable tokicos set on a stiffer setting but I think the car still feels too "soft". I have H&R springs on my daily driver with tokico hp's and I love the way the car feels. I dont know of any popular linear springs for the Z, so if you can save a few bucks up, go with a coilover.