Max power isn't good at all. It's way overrated and shouldn't even be included in an amp rating, because it's too easy to cheat on. If you decide to upgrade, a JBL 600.1 would be perfect. That Sony amp puts out 400 watts RMS (continuous power, which is what you need to look at) bridged, since you have two subs the power will divide equally between the two and give each 200 watts, out of the 300 they can take. I think a JBL 600.1 would be much better, though. A much higher quality amp.
Just noticed that's a mono amp. You can't bridge a mono amp, you can only run different impedances. Are the subs in parallel, meaning each one is wired to the same terminal? Sounds like your installer fed you a line of bullsh*t or he knows no more than you do. they should be connected in parallel running a 2 ohm load, giving 400W RMS, which is 200 to each sub.
so then if i were to switch to the sony amplifier the 1600watt max one, how much difference will i see in the sound quality? HOw much louder will i be able to play the subS?
i kno sony isnt the greatest....but its reasonably priced.