Verified answer

farad capacitors are usually used on very high watt systems, usually those over 1000 watts. you may want to talk it over with a pro before spending the money because you may not need it. oh and btw, mtx is probably the worst sub brand ive ever used. kicker is by far the best and sony and pioneer are pretty ok too.

I have heard you need 1 farad per 1000 watts so a half farad should be fine for 600W.

no cap needed, but the 1/2 farad should be fine, your only 100 watts over, 1 farad would be better, but dont waste you money because you dont need 1 in the first place, if you have a 1200 watt amp, then get 1 but until you cross over the 1000 watt point i wouldnt worry about it.

you really don't need either unless the electrical system has large voltage drops/spikes or has noise in the line.

A cap will NOT:

provide more power

cure dimming lights