your choices are pretty much the same as for us with the ZX3. The quieter systems are (from the one's I've heard). Magnaflow (my preference), Bosal, Thermal. And although lots of folks say the Borla is loud, all the ones I've heaed seem pretty quiet to me. I prefer the magnaflow since it's one of the quietest systems and uses only one muffler, unlike the others (for the most part) use two or three. This gives you the option to add a second muffler in the event you need even more silencing like if you install a race header as I did. You may also search for a used system. Since there are more ZX3's than there are sedans you may find one of these. they will fit the sedan with minor mods, all's needed is to add about a 5" section to move the tip farther back. We took the catback off of Kathy's ZX3 and installed it on Nicky's sedan and everything fit perfectly once we extended the tip out.