I have 2 10L7 subs hooked to a 400 watt class D they absolutely pound. Just make sure they're in a good box.

where are they located in your boat? Im concerned about putting that much bass in the cabin and rattling everything loose and also not being able to hear or feel it in the cockpit.

My boat is a runabout so they are mounted under the rear bench. Putting them in the cabin will vibrate everything loose, and the right size box will take up a lot of space.

Im hearing that the L7's need a LOT more power than 400 w.

Do you have your +'s and -'s tied together in the box?

Its a class D Memphis 400 watts @ 4 ohm that has had some work to handle 1/2 ohm load. Its rated @ 1100 @ 1 ohm both subs are wired in parallel.