I checked crutchfield.com about the '03 Protege's speaker sizes, and this is what displayed:
Front speakers
Front Door: 6x8"

Rear speakers
Rear Door: 6-1/2" factory speaker note
Rear Deck: 6x9"

But my question is, the '03 Protege doesn't have rear door speakers, right (I haven't bought this car yet, will soon)? Only speakers on the rear deck? So assuming that, the fronts are 6X8 and the back are 6X9? I heard somewhere there are tweeters in the front but I'm not sure..

 

rear door speakers are for the protege5 or the mazdaspeed protege. otherwise the standard sedan has 2 in the front door + 2 in the rear deck. the sizes stated are correct, people have run 5.25" speakers in the front due to shortage of 6x8" options.

the 2003 ES had front tweeters. 1" drivers. the "crossover" is really just a resistor in the wiring. the drivers are in the door sails - the little triangular dudes where the corner of the window meets your door panel. one quick way to check: if the sails have a black metal grill, you have tweeters. if they are solid plastic, you don't have tweeters. hope this helps