I think %90 of the sound is from the filter itself. Box slightly mutes the hissing sound. Most people dont like the hissing sound that occurs near 3000 rpm. I like it. If you cover the top of the box that goes away too but you loose a little bit of the monster sound as well.
Good thing is sound is only loud during full throttle acceleration, it sounds close to stock during highway cruising.
Good thing is sound is only loud during full throttle acceleration, it sounds close to stock during highway cruising.