I got a compact 3" cat from
Pypesexhaust.com for the driver's side and got a 3" Catco cat for the passenger side. I got them off Ebay so my net cost was like $40 for both. I cut the y-pipe and clamped them in but ended up having the driver's side welded for another $40. Here's my y-pipe with dual 3" cats on my 96 SS.