ALL Wilwood kits that are on ANY Z32 is an aftermarket outsourced kit. Wilwood does stand behind their outsourced dealers if the part is an inhouse Wilwood part I.e. If the AZ-ZCAR caliper breaks, you take it up with Wilwood, but if the rotor hat cracks, you take it up with AZZCAR.
Thank you for your valuable insight re: your real world Wilwood/StopTech comparison.