It'll be fine with an NA. Catbacks fit either one.
After swapping in my 7M-GTE, I kept the catback that I had for the NA until I got my Tanabe. So from that, you can see that the catback fits to either catalytic converter, and that the body mounting points for the NA are the same as for the turbo.
As for performance, I've heard people say that the more open exhaust can reduce low RPM scavenging, resulting in less off the line torque, but it will always open up the top end. I didn't bother with anything larger than 2.5" with my NA, so I can't really say.