Personally, I would stick with the ARH cats. ARH is good enough for C8.R, GT4.R and COPO.
ARH is the real deal + endorsed by Chevrolet performance. IMHO, the finest exhaust system available. Opinions will vary.
FWIW, when my warranty is expired, a complete ARH with cats (+intake mods) are my plan. You gotta breathe in before you exhale. Maybe a Griptec up top, ATI balancer down low (both OEM dia. +/-) and upgraded belt. SPL rods and arms will complete my vision..... I promised my wife, that's all that I want. Unless the C8 Z06 is awesome... but that's a conversation for another day.
Save the money for a tune (headers/intake), alignments, oil, tires, brake fluid and pads.
Stick with ARH cats.