Do you feel like you got your bottom end torque back with this added cat in the mid pipe? I want to avoid losing that at all costs—that torque is one of my favorite things about the GXIt's definitely doable.
That's what I did.
I have the DT long tube headers. I had a URD catless mid pipe and magnaflow overland exhaust.
There seemed to be no back pressure and my bottom end torque was terrible (and I'm running 4.56 gears).
I reinstalled the OEM mid pipe with cats and added O2 extensions and installed a universal free flow cat behind the factory Y-pipe.
I get some scent on a cold start for about 2 minutes, but besides that, it smells normal.
My down the road plan is to cut up the URD mid pipe and install free flow cats in there. Hopefully it will be better than the factory pipe, perform well and keep the CEL off.
Maybe I should get an intake...?