If you don't mind sitting on them for a little while post an ad up on craigslist. Some guy with an 05-10 v6 might want to drop them in for a quick and cheaper dual exhaust setup.
I only suggest that because guys with 99-04 GT catbacks were throwing theirs away and then v6 guys started wanting them. People were selling takeoff catbacks for $150 when they were the hot item.
12 Black GT500 SVT PP l VMP TVS l JLT123 l O/R X l 28x11.50Rx15 M/T Street R's l BMR Suspension l Recaros
03 Sonic Blue 3.8 / 17 Magnetic Fusion Sport 2.7 EB