Sorry for the link not working, I will try to fix it tonight. This sub is a beast. I would recommend attaching a base plate to the legs to allow you to move the sub around. I think it also looks better that way, like a poor man's SVS, of which I am :p. After using the S&V setup DVD, the amplifier was only set at 1/3 volume. Even with that, it has enough to shake up the basement for home theater. I will need to pick up a CD with test tones on it, like Bass Mekanik, to chart the sub's performance, since my older Sony DVD player doesn't play burned CDs. I also have a copy of Avia and I did the LFE sweep (I believe that's what it is called) and it rang up 92db, flat to 21HZ. This is a little tricky to monitor, because you have to try to look at the TV and sound meter at the same time to see how the sub is performing. It is also very good for music. I decided to give it a break in period by playing some CD's and it is not boomy in the least. Overall, I'm glad that I went this route, since it gives me the performance that would have cost me substantially more than what I paid to build it myself. I'm looking forward to Return of the King next week! Hope this helps.
Plus, give that Shiva a bit of time to "get adjusted." For me, I had purchased new front speakers about the time that I had made my pair of Shiva cabinets. While providing enough time to break my front speakers in, the subs were also played. After a few weeks of doing this, I couldn't believe how much better my speakers sounded and the sub seemed to perform better, too.
Once you get beyond your break-in period, be prepared for some serious "kick."
Congrats on the subwoofer, DIYing is always rewarding even if the project does not meet the sound expectations..not to say yours won't but just that the building your own speaker aspect alone is enough to fuel this hobby.