Not sure about the cat back but over axles and axle backs will probably be cheaper. That way if you get tired of them and want to switch you won't have to modify the pipes to work with a different axle back. Magna flow cat back is slip fit instead of ball ends. I paid like 340 for Borla over axle pipes from Maryland speed. Absolutely the best fitment on over axles.
OP If I were you I'd buy the axle backs and then different OTA pipes. In another thread only members who have had magnaflow catback had issues with the OTA pipe hitting the axle when lowered. From what I understand it would be fixed/or not with some fighting but you could save $$$ justing just the axle backs and lethal performance OTA pipes
Got the magnaflow from a member on here used for $540 shipped one I get them on I'll swing over to my buddies
Shop and throw a few tacks to make sure they don't move