Here's some options that will give a little more power than stock and are pretty reasonable. They are al cea-2006 compaint so the rated power is true.
http://www.sonicelectronix.com/item_...10IX500.4.html
http://www.sonicelectronix.com/item_...e-R400-4D.html
http://www.sonicelectronix.com/item_...ence-475a.html
http://www.sonicelectronix.com/item_...s-GLX60.4.html