For track use, if I for some reason (like cost....cost is a validreason) were going against the AP Racing calipers and had to choose a Z1 kit, I'd at least spend the extra for their competition kit. Their track kit looks heavy, lower vane count, and still have piston boots and what look like aluminum pistons. To me, more street kit than track kit.
The Z1 competition setup has higher vane count rotors and steel pistons and should hold up to heat much better. It's too bad pad changes require tacking the caliper off compared to the easy swaps with the Akebonos and the CP9668 calipers, and I don't think the pads are as fat as CP9668's support (25mm).
That's all theory though, because before I buy any BBK, I need to know what replacement rotor ring availability is, and replacement cost. I don't see any listings yet and the lack of rotor availability has caused some BBKs to become near worthless in the past (Stillen/AP Racing Radical kits for example, with unobtainable replacement rings)
Pad shape is the other thing that I'd need to figure out. The GTR clones should be fine, but what do the competition calipers use? Is that shape commonly supported?
In contrast AP's 372x34mm rings are super easy, if expensive, to source, and their CP9668/9660 pad shape is supported by just about every manufacturer.
__________________
@stupidtoycars | My track vids
09 7AT|MCS 2WNR|Topgunz Rotrex|Ecutek (Eugene)|Maxxis RC1|Titan-7 TS-5|OSG LSD|Rear Mount Derale Oil Cooler (WIP)+25 Trans Cooler|Fismo|G-LOC R12/R10|Zeta III L|NLR Wing and Splitter|CJM Pan and Fuel Hat|Radium Surge Tank|AP Racing CP9668
|