i bought a brand new 2" 1/2 atr system 6 months ago and the guy had the mufflers and wanted $400 for the new mufflers and could not justify the cost!
so i used 2" 1/2 magnaflows center in center out. i believe they were a little longer so if you already have a atr system you may have to trim the pipes a little cut a little then fit then cut a little more if needed. the reason i mention this i wish i left a little more than i did.
my magnaflows are a little loud and they do drone! if you want to hear them take the 2 hour ride down here to ct and i'll take you for a ride if you like.