Hm...difficult one. It's not a hyper 7 or 8 and it's not a Jammin X1 or X2.
I'm gonna go with one of the Ultras, maybe an MBX. In any case, it's not worth $300 even with that engine, which if it runs well, is decent. $300 gets you a brand new Hyper 7.
EDIT: Yeh, I'm sure of it, MBX...
http://www.ofna.com/ultrambxcomp.php