I have been useing the Z-CS for about three years (Zaino user for 13 years) on my 1996 Impala SS and my 2004 Silverado 2500 HD. I use CS with the entire Zaino process. I will start on my Camaro this week (just picked it up on Friday).
After I wash with Dawn, Clay, Wash with Z-7, I am going to use the CS first as a base coat. After I polish multiple times with Z-5 and Z-2 I will top coat with CS. Like Sal Zaino says, then get out your sun glasses.