Whats the RMS of the factory amp?
Also, is there really any point running the supplied JL crossover? The factory proscessing is going to kill the levels and freq's regardless....
Just thinking, because I MAY end up putting in my Pioneer c720-prs' that came from my other system. Don't have the coin right now to do the JL Cleansweap, amps, Sub ect...
Now if my Zapco C2K's fit, maybe that'd be a diff story.....
No idea what the factory RMS rating is, but it ain't much... they're claiming 700 total system power for everything, including the sub. Divided evenly that's 87.5 watts of "peak" power per speaker, though your probably looking closer to around 70 watts per speaker and 200 for the sub. My guess is the actual peak power is less than that, with RMS being considerably lower.
Not sure what would be a good replacement for the speakers just running of the factory amp, but I'd find ones with low power ratings (under 40 RMS) with high efficiency ratings. That would likely give you your best bang for the buck.
If your using the factory amp straight to aftermarket speaker, then any passive crossovers supplied with the speakers would not be needed as this function is handled by the factory processor and individual wires are run from there to the woofer, tweeters, etc... in fact, doing so would about guarantee that either the woofers or tweeters wouldn't work, depending on which set of leads you attached to the passive crossover.
Hope that helps.