I only have experience with CNT resonated pipes, but I've heard other brands give you a hiss as well. It isn't a "leak" sounding hiss but really like a muffled BOV. When your windows are down it sounds amazing because it's right outside your window so the sound bounces off others cars around you and stuff.
But to try and answer your original question, no it's not just CNT pipes that hiss
__________________
Z 
|