That's not really the point I was making. I was suggesting that in some
cases a cap is actually more effective. High output alternators often
suffer from the same limitations that a stock alternator suffers from
when
idling.

MZ, at the same RPM a higher power alternator will produce more current
than
a lower power alternator.

Not always! In fact, some produce less current than the stock at idle.

If you have enough power coming from the alternator there will be less
problems with lights dimming since the alternator will be producing enough
current to power both your system and lights at same time.

That's right. But sometimes (certainly not always) a capacitor will
contribute more towards reducing dimming than an alt. It depends entirely
on how bad off your electrical system is in relation to the power demands of
the vehicle, as well as the type of music and listening habits of the user.

Most of the time you need more power only for the bass. The tweeters and
midranges dont need as much power. If you have xover's then the subs and
tweeters for example won't be running at the same time, so it's safe to
assume that you can get alternator to cover your subs and other
accessories.
If you don't have xover's then you have to get alternator that will cover
all speakers running at the same time (e.g. tweeters+midranges).

I'm not following this paragraph. The alternator (and capacitor) affects
all aspects of the electrical system.

Of course, if all you have is a 100 dollar bill, spend it on cap. It won't
give you more power, it will cover the surge power needed for bass.

It can deliver a sufficient amount of current in a short enough period of
time to have a noticeable effect on headlight dimming at all rpms.

And MZ, please tell both sides of story when making a point. It's easier
to
understand why they should or shouldn't choose one over other (new
alt/cap,
etc.)

I believe I have told both sides of the story. Check the FAQ.