1800collect is right. You can get alot of noise from very little power, but its mostly to do with the box more than anything. Sundown are very good subs as well but there are rarely as cheap as the RE's from the prices that i have seen. I personally would spend the 100 or so dollars on a good prefab box like i mentioned earlier. As for those Rockford P1's, please yet again stay away from these. I've heard many horror stories and I've owned a set of two tens. On a cold day the cones of these subs will crack on you not to mention in general how bad they are on sound quality for price.
Remember depending on your music theres 3 main choices of box you can do.
Theres sealed which will play the most notes and have punchy bass. These usually have pretty good output but if you want bass, i mean BASS i'd go for something a little more powerful.
Theres ported or vented enclosures which will half some punchy bass with a longer roll off on the notes but it also will play a few less notes than the sealed. This is my favorite and is the one i would choose since they are the midrange between the other two, plus if you have to you can build one yourself. Just make sure to choose slot ports over round ports. Round ports are easy to do but they don't sound near as good.
The last choice is bandpass and there are multiple types of bandpass such as 4th order 5th order 6th order and so on depending on the number of subs and interior boxes. Bandpass box designs are best chosen for competitions. They offer a lot more power but also have a much more narrow set of notes unless you go for one of the lower orders like a 4th order box. Which is why the 4th order is the most common prefabricated bandpass enclosure.
