Please stop spreading misinformation.Small woofers and loud don't mix. For subwoofer duty, I consider 12" a minimum. 10" or 8" is a joke unless you only want a little bit of output (just blending and filling) or intend to run an array of them to achieve adequate cone area.
For SQL, I would think more towards 15" and 18" subs. Available options are plentiful. Which sub depends upon many factors: budget, size constraints, power, desired frequency response, desire sound characteristics, etc...