Actually,
power caps are great for any person with a Bass amp. I would reccomend one to any bass head. Account for at least one farad per each 1000w of amplifier
INPUT power rating.
Answearing;
A Farad counter shows how much reserve is left in the Power Cap
Although most Power Caps display output voltage.
Cheers Waynne for the science lesson. i think you could confuse a college professor into giving you an A+
LOL
In laymans terms,
Power Caps, Basically stabilze the voltage, as Bass amps need power in bursts (to the beat/bass) because the Amp Needs its close to its Rated ampage on full volume (if correctly set up).
Car batteies are not designed to give power in this demanding way, and so the electrical voltage keeps dropping and surging, (not good for ANY other electrical devices inculding all bulbs), Car battery also lasts longer in my experience with a power cap. Also you might notice an ICEd car without Powercaps will develop a squeeky alterntor pully
Also Note that a voltage drop in a Petrol car,
Will mean that the ignition coils hav less voltage, & lead to a Lesser spark, (less powerful combustion = less power).
[on average - not a really noticable in upto 500w installations]
although, its not often you would crank it right up an thrash the car at the same time.
But primarily, these Power Caps aim to hold charge like a short term battery and discharge it quickly on the beat/bass.
This also Means that the Voltage stays higher,
THUS more volume before the amp starts pushing out distorted signals.
By the way, [
my science lesson]
if you multiply the amps combined fuse ratings (they sometimes have 2)
with the supply voltage, You get the REAL POWER Wattage that the Amp is trying to live up to.
eg, 80amps worth of fuse on my amp, multiplied by 13.5V =
80 x 13.5 = 1080w
heavy bass amps can reduce that voltage to 10 on a running car
80 X 10 = 800w
And those Wattage quotes are for what the Amp uses and not the RMS (output) wattage.
Also Note that Most amps are all Less then 50% efficient,
[CLASS D amps are up to 75% efficient]
BUT, now you can understand why the voltage gauges are there.
So you know what you're getting.
By the way Kids, that technique of checking the fuse ratings on the amp, really helps to tell the real power amps, from the cheapy air filled hunks of metal with BIG Ratings. But Cheap Amps tend to be less efficient so be aware. (EG "Legacy")
Budget Amps brands will often rate their amps o a 14VOLT basis.
i think i hit this one out of the field Waynne.
But anyone can correct me if i'm slightly off on the efficiency ratings.
Farad? or Fad? 
. A farad is the capacitance of a dielectric for which a potential difference of one volt results in a static charge of one coulomb. It has the base SI representation of s4 · A2 · m-2 · kg-1. Since an ampere is the rate of electrical flow (current) of one coulomb per second, an alternate definition is that a farad is one ampere-second of charge at one volt. 
Why did he buy a gauage for it?
Linear Mode
