Several of the points you mentioned which I will attempt to provide a relatively brief response to, for sake of reading time
First, about Tazer's comment refering to the capacitor as a bandaid to a weak electrical system: What I think he meant was that it will not correct or help an overload condition on an alternator. This is true, because a cap is nothing more than a temporary storage device. Like a water tower, it can act as a buffer in that a large electrical draw will take from it rather than the alt, but then it must refill. If alt does not produce enough, the cap will eventually run dry. These processes occur in seconds when dealing with the large current draws found in car.
Next, you implied that with the power of his chosen amp, the stock alternator will likely be fine, maybe challenged at times of highest acc use. I agree. It takes a relatively powerful amp played at a good volume for a good percentage of useage time to really exceed alternator output. Most ppl do not have car audio setups like this. And for those time when accessories are on full w/ amp at high volume, he will likely be ok if alt output is not greatly exceeded for long. Again however, if it is, a caps storage will run out quickly. It can not store enough reserve power to make up a possible alternator lack of output even temporarily. Calculating the current draw of his amp & matching it to available current is a good way to determine what will happen, but like stated it is likely fine with that power level.
Third, the alternator can be damaged from extended draw over its rated output, as I mentioned earlier & as you have. However, as far as components damaged from a large amplifier taking more current then available through the cars electrical system, the alternator is really the extent of the possible damage. Wiring issues are seperate. Anytime you have a large unfused wire, there is a possible fire hazard reguardless of alternator or amp ratings. Like I say, if there was an instance where amp draw exceeds alt output, it would be fine to just play & see. Only the alt could burn out from this, and it just means it needed upgrading anyway
. As for smaller wires, they won't hurt anything (as long as they are fused) but the amount of power your amp will get will be less.. so output could be less. It would be little more than a waste to have a good powerful amp and a 20 gauge wire to power it. Only a significant lack of output from the amp would result.
To recap, first I should say my intentions are not to be on the offensive here. I like car audio, and hence its discussion. Basically the use of caps to compensate for electrical system inadequacy is just something that I see happening a lot, but know it doesn't help in that circumstance.
In this circumstance, I do agree with you about his amp power in ratio to his stock alternator, I think it is fine too, even on those rainy days. A cap could serve to protect his other sensitive accessories from the regular voltage spikes which occur as the amplifier draws and stops drawing current.
Someone I know has an MTX amp producing 500 watts @ 2 ohms pushing 2 10" 6k series on a stock alternator setup in conjunction with amplified mids & highs just fine.
There is something you could do short of replacing the alternator to help if an electrical system is found to be inadequate.. upgrade the magic 3! These are the various ground wires found inside the engine bay, and can make a significant impact!
Nice discussing with everyone...