still a novice at car audio.
i have earthquake amp tnt1000wx2 amp with polkaudio audio 12inch dvc 700watt/380rms .

i think amp is bridged 8ohm load to the max to work with the DVC Sub but on peak volume, the sub is not reaching its max excursion. the bass is ok but it should be louder.

incorrect Amplifier for the Subwoofer? or incorrect subwoofer for the amp?

amp Specifications:
•Model nr.: T-1000W-2
•EAN: 0-168975-910325
•Class: "A/B"
•Channels: 2
•THD: >0.005%
•Signal to Noise Ratio: >95dB below rated power
•Max Power: 1400W
•RMS Power 2-Ohm Stereo: 2 x 300W
•RMS Power 4-Ohm Stereo: 2 x 125W
•RMS Power 4-Ohm Bridged: 1 x 400W

 

Max amplifier output is at 4ohms mono. Your sub is wired for 8 mono and can't be rewired for 4 mono so the two are not a good match.

 

Also, if it's in a ported enclosure, it will have the least amount of excursion when its at it's tuned frequency.