right, its my opinion and some disagree but here goes....
Ditch the 6x9's. In fact, ditch the rear speakers all together. Use the amp to power a sub and some component speakers in the front and hey presto. The reason is the sound stage is brought to the front of the car, where you are, rather than be dragged back into the rear, where your not. Its the set up i have in mine and il not have it any other way.