Been away for a minute. Not running any programmer(s). As for gains, I can't give you numbers like from a dyno run but the difference is real. Had a Gibson 3" catback as well at one time but felt there was more to be had with true dual set up, so that's the direction I took and I think it was worth the effort. Gibson CFT's mufflers. Thanks for looking.
Been away from forum for a minute but yeah, I deleted the "unmonitored" cat. And it didn't cause any codes to pop. Shops are in a hard spot when it comes to this sort of thing. I"ve researched it quite a bit and no one can give me a credible answer as to why the damn thing is there to begin with. Some have even tried to tell me its a "resonator". Who knows, but again, it doesn't generate a code that has to be rectified. Hope that helps. Thanks for looking.