Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Catco or Magnaflow two inlet cat part #s?

I've got a SHO-Shop y pipe with the 2 into 1 main cat, similar to what BAT and SP now sell as part of their 2.5 duratec y pipe packages. A shop now doing some work and tuning on my rig was getting low power #s, so they tested for exhaust sytem backpressure and figure my main cat is rather clogged. I'm striking out so far on finding which Catco cat (or does a Magnaflow subsidiary make one?) part numbers most closely match up to swap in for what I have. Anyone have leads or a clue on a likely match part number? All the parts houses on line are oriented to tell me what replaces my OEM main cat which is NOT a 2 into 1.