If you want my advice, I'd say don't bother changing the speakers for starters. For some reason, the headunit on the new toyotas (Corolla and Rav 4 as far as I know) have weird logic behind them. The EQ doesn't quite have the proper balance. Listen to it for yourself, use the fade option and listen to the speakers at the front, then fade it to the back. I don't know why but the ones at the back sound absolutely awful. I went to a Autotainment and they recently did a RAV 4 (same headunit as the new Corolla Conquest that I have), and they changed all the speakers and powered it via a 4 channel amp. Still sounded crap and customer wasn't satisfied, so the bloke ended up paying an extra 300 and bought a half decent headunit and apparently blew the customer away :) Obviously, thats what they said. Really though, if you're after good quality music, I personally would change the headunit first as well. The back speakers wouldn't make much of a difference...and if you're going to get new speakers at least power them with an amp. I've been going around looking for a new sound system as well..