Ah, great. If one of the other models has one, would it be easy (or has someone else already) fitted the subwoofer model from a limited onto an sr5? Is there some wiring already in place, etc.?
It's just a stupid little gimmick. Depending on the stereo you have, it works a little different. It's meant to boost the bass a little and send more sound to to the rear hatch speakers and less to the back doors.