Generally, the installation of a CGW Reach Reduction Kit will reduce the at rest SA trigger position by some amount. It depends on what disconnector you have installed before you replace it with the CGW RRK disconnector and which CGW RRK kit you are installing. The at rest SA trigger position is a product of the thickness of the inside of the disconnectors hook.
In a Shadow or other non Firing Pin Block CZ model, an oversized RRK disconnector can be hand fit to achieve near zero SA pre travel. In a CZ 75 B or other CZ with the FPB intact, you are somewhat limited in how much the SA pre travel can be reduced. This is because the FPB parts require a certain amount of SA pre travel to function.