Yeah Mine are the MTX JH45's 4 ohm 250 rms 1st link. That's individual.. the box specs are 2nd below and they run them bridged. I got the amp and box at the same time. Of the amps and boxes they had this was what I could afford and I tried to match the amp to the subs. They didn't have a ginormous selection

purchasd in store at Frys + had them do install.
To be honest for the price of $100 I think the 8501D is a good value. Go to Crutchfield and do a search for class D subs under 115 bucks and see what options you have. I think it's a great amp for the crashed strapped average joe.
Now If I were to step up to say the Polk box running 2 12" subs I would probably get an amp with a little more power but as it stands I think that's a super match of amp and sub for under $300.
http://www.crutchfield.com/S-ghVEFFq...JH4512-04.html
http://archive.mtx.com/caraudio/prod...Enclosures.cfm