Staying stealth now days is not a bad idea. If your looking for an aftermarket cat back, look for one with a resonator and make sure the resonator is a staight through perferated core with a consistant diameter. Some systems now days come with some sh!tty louvered cores with a 2.5 or less internal diameter.
If your really serious about sound and want to stay under the radar you might just mant to take things into your own hands. Source the bends, muffler, and two resonators yourself. Find a muffler shop that can do the job and have them weld it all together. Have them base it off the stock cat so you can swap it in for smog tests and you can still pick up your choice of aftermarket downpipes. Basically have them build you a stock flanged testpipe and catback. Maybe have them include a resonator in the testpipe and one in the catback piping and paint it all flat black.
