Stock OEM cats are warranted to 50k miles, looks like you're 30k past that.
I'd call the dealer and see what they say. They might take care of it for you, or maybe at a discounted price.
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Bobby
Died 5/1/08, resurrected 5/15/08
ASCD SD hood, 17" Bullitts, Overkill PCM, 3.4" Pulley, NGK TR55IX, K&N 9" cone filter, JimmyC D/P, U-bend removed, Flowmaster 40 series, Hooker big bore tips with resonators, S/B brake lines, drilled/slot rotors, GMPP handling kit, KYB struts, F&R strut supports, HID's, LED's, 2.5" Air Dam, red GTP overlays on custom badges, white rear insert.