I have an Eclipse 3650 amp, specs for which are:

5/4 channel power amp with channel flex crossover plus subsonic filter
40x4 at 4 ohm
120x1 at 4ohm
2ohm stable design
channel flex xover
Adjustable high-pass frequency (50-200hz for front)
high-pass frequency (120 for rear
Adjustable low-pass frequency (50-200hz for subwoofer)
Is it worth wiring such an amp to something like this in the front: Newegg.com - Infinity Kappa 42.9i 4&#34 150W 2 Way Car Audio Speakers

Also, should I upgrade the front 4" with something like the ones in the link, or the rears first? I would like some good mid bass frequency but I was told I should upgrade the fronts first which I know will have no midbass. I don't really even care if I have 4 channels, I think 2 would be fine.