Tom, I have run five times on my Z-2's, and they show no noticeable wear yet. I have same size F&R, so I rotate each event. They seem to hold well, but I have nothing to compare to since this is my first set of "200"s. I have been having more trouble keeping fuel to my main jets while hard cornering. I finally swapped out my Thermo-quad for the AVS, and saw much improvement. Bowl shape on TQ not good for hard cornering. Are you running a Holley? I have a few, but never cared for them on the street cars. I have a 630 cfm AVS on it now, and I am prepping a 750 cfm for later. Take care, Rick