went to local stereo shop (soundsgreat) here and they bought termlab meter. Played 36-42hz tones and highest was 147.3. Played lil jon (throw it up) and did 147.1, both scores with windows up, doors closed. Happy with that, I am sure after some more deadening and maybe another d3100 it may do more. But thats plenty, its just my daily driver. Really impressed with the sundown amps and fi subs