Looks like you play a tighter game than me. I got a close score to yours while reaching level 8.
EDIT: You get a 1,000 point bonus for clearing four or more blocks of the same color in a chain.
EDIT: What determines the set of bumpers at the bottom? The big bumpers move around sometimes.
EDIT: Looks like Bal Cube isn't very competitive on Twin Galaxies:
http://www.1337live.com/scores.php?scores=7268