Power caps rob all the power from amps when they need to recharge them selves.
A normal car can cope with 1500-2500wrms without much upgrading.
From what i can see, you don't really need any power upgrades at all, if your lights are dimming i would make sure all the amps are set up properly.
No bassboost at all. Gains shouldn't be more then half way in most circumstances, set all gains to the headunit at 90% volume and stick to it, any more can cause the headunit to start distorting its self, therefore the amps amplifying a distorted signal in the first place.
If you find you still have dimming lights you are best off doing whats called 'The Big 3' Basically upgrading the power wires under the bonnet with bigger cable, 0awg preferable, Alternator Positive to battery positive, Engine earth to batter negative and battery negative to chassis.
In my competition car i had, 4 very large batteries capable of 20000amps of current, 250A alternater upgrade and miles of cable. It was doing in excess of 153 decibels though, made the windescreen move ect ect.....
