It's a muffler delete, and it looks to be a very high quality one. You're comparing it to the Perrin cat back which is made for the hatch, so it is a totally different design. If I had to guess the one with no mufflers at all (Nameless) will be MUCH louder than the one with a muffler (Perrin). It's just an axle back so you're only really buying it for sound. If you like the sound and want something loud, it looks to be a pretty nice piece of work.
Nameless - Any plans for a quad tip axle back for the hatch?