I found a post on my local Craigslist for a S-Tune exhaust, but only as the muffler not the mid pipe and muffler. I have been digging up some research between here and the guys on the my350z forums and everything is saying that most of that vq sound is generated with from the y-pipe and mid pipe. If anyone with experience could chime in to see if it is worth attaching it to the stock mid (berk HFCs recently installed) or the closest thing I found to a non oem mid pipe on its own was a megan racing one claiming it can connect to an aftermarket exhaust

 

Whatever you've been reading is erroneous to a point. The Y (they're the same for coupe and sedan) and mid pipes do affect the exhaust tone but the muffler is the biggest difference. Case in point a lot of sedan owners go to a coupe mid to change the exhaust tone slightly but also to drop some weight. The sedan mids are heavy...

The S tune is a great sounding system so I'd jump all over that muffler if I had the decision to make. Just don't expect to see any HP gains.