Never heard of that happening. If you want to get cats, go with the Magnaflow/Carsound hi flow cats. They're relatively inexpensive if you don't get the premium cats, and they work great. I think I got a replacement for my old car (93 Caprice Classic w/ 5.0) for $60 shipped on ebay.
If you're just gonne run straight pipe, any muffler shop should be able to cut and weld them in for you.
07 Silver AWD TBSS; Magnaflow, res delete, Jetttstream intake, GSS Tune [13.75@99]
08 GC SRT8 HPE530 #13/50--Airaid CAI, Kooks LT's, Corsa cat-back, Ported heads, DiabloTooned, H&R Springs