I mam considering staying with the stock downpipes but removing the 2nd set of cats while replacing the front set with a pair Of PYPES steel cats for forced induction motors. For the muffler, if a 14" body Borla can fit I would use that, not sure about the resonator. I suppose I would try the system without it.
The Borla is a SS piece with dual upswept tips. I'll look for the part number. Sometimes large diameter downpipes/exhaust systems hurt torque for a few high rpm HP where it is almost useless. Anyone whp has actually tried reworking the stock pipes please share your results. The Borla part # is 40059, SS with dual upswept tips. If I do this I would do a before and after dyno pulls to see if what I have is mind would yield at least 15whp, which is what I have read the NW downpipes make with all cats removed using the stock resonator and muffler.