What is the stock exhaust system on a 2001-2002 Camaro SS?

I am confused as to whether the SLP dual / dual exhaust system was the standard exhaust or not. If the SLP dual / dual exhaust was not standard on the SS, how was the SS exhaust different from the Z28 exhaust?

 

The dual/dual was an option.

Standard exhaust was a 2.75" piping and single in/dual out muffler w/round tips. The difference was the muffler and tips IIRC.

 

Two more questions:

What was the piping size for the z28?

Is there much of a gain going from the standard SS mufflers to the dual / dual mufflers?