i have srs catback + helix catted dp + apv1 ots stage II. i tested the sound level using a radioshack sound decibel level meter.
06 wrx exhaust sound level testing- Video
i placed the sound meter 45 inches away at 45 degrees from the tip.
its on the loud sound side, and personally a lil too loud for my ears. thinking of toning it down a bit with a different catback. although, i love how it sounds going under a bridge or through a tunnel. seriously its pure ecstacy