The Wet Sounds HTX-6 would five you 100W rms for each in-boat and 300W for a mild woofer. The Syn-DX6 would be a step up in woofer wattage to 600W. Both of these options would allow for a 3rd pair of in-boats to be added. I would suggest this, if you went with the 600W rms woofer option.

With that said, the Kicker KXMA800.5 is still a solid option for a good setup. The in-boats are still going to sound great even with its 50W rms to each. Wattage is not the whole story, a quality amp makes a huge difference in sound quality compared to low quality amps that boast high wattage. This amp also includes a wireless sub controller.