Sometimes you can find that sort of info on Crutchfield's site by looking up
what fits your vehicle.
www.crutchfield.com

The factory Infinify amp is nothing special - it's about 15-20 watts
RMS per channel (if that), the peak power rating is 40 watts per
channel as specified in the Dodge literature.  Most decent aftermarket
head units are more powerful.

One thing to note: The front speakers are "component" speakers in that
they use a crossover to separate highs from lows.  You'll need a
separate woofer/tweeter combination to replace them.  If you're just
replacing speakers and leaving everything else alone, you won't need
the crossover itself, as that's built into the factory wiring.

Also, due to the relatively low power of the Infinity amp, you'll want
to get the most efficient speakers you can find.  A SPL (sound
pressure level) of 92 or higher would be good.

Regards,
Joe