Soundstream - These guys make some of the best amps I've ever heard. Period. I don't care that they are inexpensive, I have three Rubicon 502 amps in my car and they outperform every other amp I've ever had (with similar power ratings). And I've run Phoenix Gold, Sinfoni, Audison, PPI, and Hifonics. I like the Soundstreams the best. They are super clean and seem to put out about 10 times their rating.
Alumapro - The cleanest hitting sub you can buy is the Alumapro Alchemy RX. These things put out bass that can't be described with words. You don't hear the bass, you feel it. They also make lesser model ($65-$170) subs (Alchemy MX, and Alusonic) that are on par with subs that cost in the $250-$450 range! Alumapro also has a very rare super duper SPL sub called the M-16... that thing is dangerous. I saw one M-16 with a Zapco C2K-9.0x amp hit 158.1 dB!!! Alumapro also makes the best Capacitors money can buy. They manufacture the things for MANY other companies (Phoenix Gold, Audiobahn...).
I hope that info helps.
BTW - Check my sig, I might be slightly biased. But I love my setup!