I've been hearing a lot of talk about needing a capacitor so I got one. I installed it in my van behind the driver inside the panel with velcro. I don't notice any difference in my system though. I have a Yellow Top deep cycle battery and it came with a beefed up alternator and a volt meter. The cap20 shows me digitally what I see on the gage in the dash. I don't detect any improvement in sound quality after installing it. I guess you can't believe everything you hear until you hear it for yourself.
to respond to the last post a cap has nothing to do with sound quality its more about your batt and from what u have listed (alter and optima) u would not need a cap a cap helps by keeping the batt from draning rapidly insted the cap will diss charge the power in a fraction of a sec. and keep your lights from diming and keep your rpms from droping .....ect. but for ppl who r not making more than 1500watts a cap is a good alternative to upgrading (altternators and batterys and motor and battery grounds)that "most" ppl will never need
Steve, did you charge the cap first? Insstall it correctly (positive to cap, then to amp, grnd to grnd then to gnd source, not to amp)? what cap did you buy? Lots of things can influence how your cap will perform.