znahumThat sub is decent enough. But what you really want are the DIY Dayton Ultimax's. Just did a sealed Dayton Ultimax 18" build and it is a complete monster. Does cost more as the driver alone for a 15" is $200. Well worth the jump.
BigTerminatorI was considering making the Ultimax 15" build for quite awhile however I couldn't justify paying that much for a subwoofer and amp that was needed to run it.
znahumYou really should justify it. A sealed sub that can do 20Hz flat is a whole other experience. When I get my 2nd 18" Ultimax built I will be in the hole for $1300 including amp. And hell yeah it is worth it. Comparable to subs costing $1500-2000 each. Love my Rythmik L12 for $540 in the bed room, but I might have gotten a 15" Ultimax instead if I knew I could make em. You could probably do the 15" build for $450 which is a great value when you look at the going rate of a 15" sealed sub with a 500+ watt amp.