Havent seen a stock exhaust in a long time but isnt it welded on? no bolt flanges that i recall for just muffler.
Id just go to a mom n pop place and ask for a replacement and chose from the standard players.... all will be a bit louder than the stock system
Borla has replacement parts listed for 80 specifically and are probably the quietest but still louder than stock.
walker, dynomax, magnaflow, flowmaster (80,70,50,40) are probably a good guess in order of quiet to obnoxious

several threads on here if you search exhaust to see what others have chosen.