It would be really sleeper if it was freer flowing than the Z's, their mufflers look almost the same. Do they have the same mounting points?

 

Umm, the S-Tune looks identical except for the polished can (which is hard to see unless you look for it). Much better exhaust, and a known direct bolt on.

 

And to be honest, the muffler on the 350Z isn't a serious flow restriction (according to years of discussion and dyno testing on these forums). The problem really seems to be in the stock cats and y-pipe. Replace those two items and you'll have a 90% stock sounding exhaust and 100% stock-looking exhaust. That's the ultimate sleep in my mind.