What is your price range for a woofer?
Hsu sells a 10" car sub that isn't too bad. There are also other good offerings out there from Infinity, JL Audio, etc. In terms of absolute quality, I'd rate JL as the best (or one of them). They are expensive (and some members will say not worth the price), but their drivers are made with high-quality components and exhibit low distortion and high linearity. And they can bump too!