from wat i hear very good. Brahma and tumult are the models most talkd about. I think the Brahma is known to be very efficient maybe??, could be wrong. They used to get talkd about alot more tho, havent heard it mentioned in a hwile.
The brahma and tumult are great subs though...but kinda over priced now. I used to have a brahma MK2 10" that I bought new for $360...It was amazing.
By far the best sounding sub i have ever laid my hands on...1.6cuft tuned to 34hz w/ 600w under my back seat sounded like a drum in the back w/ rock songs. Metered within 1db of 2 CVR 12's on 800w...I later put 1200w on it and did 138's on the dash like it was nothing. People used to freak out at comps when i showed them it was just 1 10".