One of the mufflers I have at one time on my 2001 S was a 2003 S muffler. I had if modified by FD Motorsport.
FD Motorsports » Fister Exhaust – Boxster/Cayman It was by far the best sounding exhaust I have heard on a Boxster. And, that was with the secondary cats in place. To get some decent sound out of the PSE I had to remove the secondary cats. As much as I like the looks, rarity and uniqueness of the PSE, I prefer the sound of the modified '03s.