Short answer, No...
You are looking at 1000w for the sub amps, and then say another 400 or less for the 4-channel. I don't see that draining your system. In my truck my sub amplifier is wired up to feed 1500w to the sub, and the 4-channel is rated for 400, but probably putting out around 300, but I have yet to ever have a dimming issue with stock electrical.
A capacitor is a bandaid at best to a bigger problem, or is just a really tiny battery in the electrical system, that now the system will have to recharge when the capacitor is drained. The best way to do it, if you notice a dimming or electrical drain issues is to first upgrade your charging and ground wires, commonly referred to as "The Big 3" basically upsizing the wire from the alternator to a 1/0 and also the grounding wires from the motor and the battery to 1/0, and in our trucks the wires that connect the batteries since we have a dual battery configuration.
Then if the wire upgrade doesn't alleviate things your next best step is either a larger alternator, or adding a third full battery like an optima yellow top.
Basically the electrical system is like the fuel system in our truck, the larger the wire/fuel line the more volume can be supplied with less pressure drop (voltage drop) and a capacitor added into the system will be close to the equivalent of a fuel bowl or the secondary filter housing versus the fuel tank, it is just a small amount of volume that if drained will take a little bit to replenish.
Hope this helps.
