I'm still fighting with this exhaust system. The pipes fit right, it's just a pain working below. I saved all the exhaust hangers and insulators from the CTS to use on the new system.
I used the original catalytic converters and pipe assembly up front, then put full size (quiet) mufflers on. Now the tailpipes. When I had the tailpipes bent, I had them done all on one plain. I knew that I might have to adjust in length and angle where the pipes spread out to go around the gas tank. It turned out that I was a little long so rather than lop 1 1/2" off the front of the pipe I took it off at the bend. That made it easier to assemble the last section with the resonator, exhaust tip and hanger. Everything fits but it's getting pretty busy back here behind the skirt.
From below, it looks like the pipe hangs low because the gas tank isn't in yet,but if you look beyond the pipe, you can see that the frame rail hangs a couple inches lower than the pipe.