some brake questions about my system

[Grnova]

I am running 13" slotted rotars with 6 piston calipers up front stopping an 18" tire on my DSE nova front end. Have a manual wilwood 7/8" master cylinder. And on the rear I have 4 piston rears on 12" drilled and slotted rotars stopping a 335/30/20 tire.

I have worn the slots off of my willwood slotted rotars only about 75 miles on them does that mean they are done and I need new ones?

Also I have a proportioning valve on the rears but do not think it is doing anything. I want to get everything I can out of the brakes so anything you see wrong let ne know.
Thanks





Rears