This peak in output can be a good or bad thing. If you want a loud, boomy system, then you'll want your overall Q to be higher (probably over 1) so you can get the speakers to produce a big, loud volume peak. If you're more into sound quality, then that big peak in output won't work very well since your speakers won't have a linear, smooth frequency response. A sound quality system should have a Q of 0.7-0.8 to get a tight, snappy and accurate type of bass. This discussion assumes you are using a sealed type of enclosure; a ported enclosure works differently, but we'll discuss that next month.
Another important woofer characteristic is excursion, which is basically the distance the woofer can move from peak to peak. This one's a no-brainer: if you move the woofer more, then you move more air and make more bass; it's a simple as that. Most good subwoofer manufacturers have focused on this parameter more over the last few years, and we now have some woofers with several inches of excursion. The only problem is that it takes a lot of power to move a woofer that far. Again, it's important to be realistic about your system. Don't spend over $1000 on a sub that can handle 3000 watts and move three inches peak-to-peak if you're only going to put a 300 watt amplifier on it. Find a woofer with good excursion that works well with the power you have, and go with that instead.
That pretty much covers woofer selection, so next month we'll discuss enclosures, impedance, amplifiers, and how to get it all to work in your ride. Keep those questions coming to sbrown@alpine-usa.com, and I'll see you in the lanes.