I jus did an install in a '02 IS300 without Nav. I put in an Alpine indash screen/tuner along with a DVD changer. The customer only added a sub amp and enclosure, the remaining speakers were the fcatory setup. His alpine is powering the front doors and the rear high freq speakers. He opted to leave the 6*9's out. I crossed over the the rears at 1000 hertz as they are only 2" paper cones, and the front at 90 hertz. The sub is running 90hertz and down. The customer is all upset because a moderate volumes the fcatory speakers start to distort something terrible. They are very cheap and the Alpine power actually is greater than that of the factory amp, thus the problems with power handling and distortion. I post this for those of you that are looking at doing this setup. I just want to prewarn that disappointment may occur.