It's a class b so a little power hungry compared to a class d. Just make sure you have big 3, a good battery and 4 ga power and ground. A second battery really wouldn't hurt to keep the volts up. It is very hard to maintain 14.4 volts, especially with a class b that is power hungry. Overall it is not a bad amp. They are very quick to clip since they are power hungry and drop voltage on a stock vehicle quite a bit more than a lot of class d amps. If it were mine and I planned to stick with the single l7. Or a comparable sub for that matter. I would just upgrade the electrical and not worry about another amp. If you intend to upgrade your sub or go with multiples, I would look for another amp. The one you have is more of a sq oriented amp and also needs optimal conditions to make rated power. As for mid price recommendation,
AUDIOPIPE 3000W AMP 1 CHAN CAR MONO CLASS-D AMPLIFIER - eBay (item 360276357153 end time Jan-23-11 14:54:53 PST) a very flexible amp. On your dual 4 ohm coil. You can just run it as a 2 ch, 1 to each coil for 1200 rms. Later on it can be ran at 1 channel on a better sub, or multiples. If you are happy with your sub disregard and save the money by staying with what you have. If you are not happy, odds are it is the sub. Although power hungry that amp puts out cleaner power than a lot of the sq oriented brands. It is just hard to put it in an spl role without a very good electrical system.
Good luck.