Fuel pumps don't have a return line, unless it's just a fitting on the mounting plate. It's still not part of the pump, just a separate fitting on the mounting plate.

If your engine has a return line, there should be a pressure regulator attached to the back end of the fuel rails on the engine that sends the fuel back to the tank. The tank will have a return fitting on it.

From what I've read, the CTS pump supplies the correct 43 psi.

Newer engines, like the LS series need 58 psi. There is still a return line, but it comes from a fuel filter/ pressure regulator located near the tank, that sends excess fuel back to the tank. That system eliminates a lengthy return line, like the older systems use. I have an LS3 in my car and it uses the newer filter/regulator system. The filter/regulator is mounted right by the tank and has less than a foot of return line.

The link below has a diagram of the fuel rail and pressure regulator location on an LT1.

Fuel Injection Basics - Tech Article - Chevy High Performance Magazine