Alright so I used to build subwoofers for myself and close friends. I have been busy with a new job and havnt had time to do it for about 2 or 3 years. The last sub i build was an Adire Audio Shiva in a large box, i believe it was 6-8 cubes tuned in the low 20s with a 250 watt plate amp. I want to build myself a new one and i want it to be louder than that was. I havnt been reading about home theater in a while so im dont know what everyones using now since i believe adire audio is out of business. Im looking to use a 500 watt plate amp and box size isnt much of an isssue. Budget is under 500 for the sub alone. Can anyone reccomend a sub that fits my requirements? I could use a larger plate amp if neccessary. I want it considerably louder than the Shiva and 250 watts was. Thanks in advance.