Speakers, amp compatibility?

[blindsidedmtjac]

I'm looking to install four new speakers and an amp in my Jeep Cherokee. I've decided to get them online and i've got a buddy who says he'll install it all.

I'm not a huge car audio buff, so I was first wondering if theres any compatibility issues to look out for when choosing speakers and amps?

Also, I was wondering if the specs seem reasonable?

I'm looking at:

2 infinity 5 1/4" polypropylene cones

(I've been told multiple times that 5 1/4" is the standard size for all four speakers in a 2001 jeep cherokee? however, several online sites with compatibility checks are giving me conflicting info...help?)

Power acoustik 1600w Class AB Bridgeable 4-channel

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