Originally Posted by Bullit79

There's a DIY where a guy cut open a Nismo muffler to make it less restrictive (and louder). From the looks of the internals, it looks like a pretty standard muffler design so my GUESS it that the Nismo muffler is not any less restrictive than the Base muffler.

Link: DIY - Modified NISMO Exhaust - better sound, better power

I had the OEM Nismo cat back on my Base for a couple months. At WOT it honestly didn't sound much louder than stock. I noticed more of a difference while cruising / lower RPMs. It's a tad louder and has a slightly deeper tone to it. I read one thread suggesting it was the dual pipe design of the Nismo that attributed to the sound difference, not so much the muffler. Hope this helps.