Back when i had my 2001 Pontiac Sunfire (same body as cavalier) I fit 6.5" Phoenix Gold RSDs in there and they barely fit, so I think you may be able to fit other 6.5" speakers..not totally sure on that on though.
I have a set of 5.25" Polk MOMO speakers in my 2004 Kia Rio.They are from last years lineup and they are great off of 180 watts in my car. If you have at least around 150w i would suggest them, but only if you cannot find the Hertz your looking for as I have a feeling (but am not sure) that they will have better midbass than the polk. The polk
5.25 or
6.3/4 are a very smooth and detailed set which i believe has only changed slightly from the model
I have besides appearance. I find them to have a more in your face sound compared to some good sounding Sony tower speaker 3-way set I have. They can also be laid back on lower volume but is that respect don't shine until you turn them up in the detail range as much as the 3 way Sonys. Keep in mind the Sonys in my room have a 12" woofer, 4" mid range, and 3" tweeter all paper (for detail). Also, compared to a set of high end computer speakers (Logitech Z-2300). They have the high end extension that my comptuer speakers lack and get much much louder, yet don't quite match up tonally to the Logitechs (which have amazing tone for two 4" drivers and an 8" sub) (your gonna need to spend more than 200 for that in the car). They are a mix of tonality, detail, and loud punch, and believe me they get LOUD.
I would say they are a great bang for your buck at 200 and it will talk you a good couple years to get the itch again if you are moving from stock speakers to the Polks. The main reason i bough the Polk speakers is because i needed a balance of sound and until I had the money to spend on the high end speakers these would have to do. There may be other speakers which excel is other areas or even come close or match the Polks, and those could be the Hertz (could match or exceed), but from my experience I think that they are pretty awesome!
