I just upgraded to a 220 amp alternator (never really noticed dimming at 130amp stock) but one day it just died. I have a kx2500.1 (2500watts rated) amp in the trunk pushing a kicker solo x 12 (pulling about 1250 max due to the impedance). I'm about to get another solo x to get the full 2500 watts plus maybe another 750 for door speakers. I've had some say get a cap or two and some say get a second battery set up. The messages have been so mixed that I am not sure what to do. I can't afford to burn out this $500 alternator. I searched some of the previous posts about the second batteries and caps. There was no clear concensus of if you have this many watts then you need this particular set up...
Can we set the record straight?
I think the general concensus depends on what exactly you want out of your system. it sounds like you're trying to get something really impressive, a "can handle anything" system, so short answer is, I think you'd be better off with a second battery.
every amp has capacitors (sp? it's late...) already in it from what I understand, just not very big. they just store energy from your alternator, and your amp reaches into the cap when it needs power. if you're playing music that has a LOT of bass (like most hip hop/rap), and the cap is constantly draining and recharging, then it's really not doing much but being a middle man for the amp.
a second battery will, in the end, give you more power/backup power than any caps really would (to a certain extent...but I'm trying to be realistic here).
other than what I've said, caps look cool and get some wow-points from people who're easily impressed.
I am trying to deafen anyone who rides in my car with heart seizing bass! I saw a 40 farad cap for like $500 and I was quoted a second battery install (with an optima yellow top) for like $400 (I might do it myself if I can find a good enough how to) so the prices seem in the same range. I want to wow more with sound and not really trinkets (I haven't made it to that level of whoring yet) in the trunk next to my daughters stroller...
I guess that's 1 for the second battery install...
Thanks
+2 for the battery, and an HO alt. Those two alone would be good enough to get it going. Amp on the other hand, that's your real limit right now. I'd say try to find a pair of Mark Antony 25 OPCM (sp?) and throw those on the one you have. They are current hungry little bastages, but if you feed them the right voltage and the right load (they like .5 daily/.25 for burps) they make insane power. I think with 16v and @ .5 ohm they make like close to 3kw a piece. A guy on SD was selling a pair, he wanted 300 a piece for them. They were in a van, on 6 Selenium 15's in a wall doing like 158.x on the TL mics. Not too shabby for an amp that's rated for 350 watts for IASCA/USACi.
Kef
2 for a second battery set up
Thanks!
I am not a psycho. I would never deafen my 2 year old daughter or my 7 year old son. I'm actually a nurse and understand the effects of loud music. When the children are at grandmas and I actually make it out to chill (not very often) then I like to do it up big! I actually want them both to become doctors and they will need thier ears to listen to lung and heart sounds. Hey and maybe repair the ears of the people I deafen with my music... I am responsible.
Ya plus I made the box soo it can't be that loud LOL
2500w isn't all that much to worry about in real world situations. Nice battery and the new alternator shoudl be way more than sufficient.
How about getting a digital voltmeter instead of using your lights for that role - there like $10
a 40 Farad cap is just silly, your far better off with one or two small caps. Best solution add a good second battery ($120 - $160) add a cap to that along with the ALT and you should be good to go for any musical situation. Sweeps and other test tones on the other hand may still cause voltage spikes in the wrong direction. Adding a second battery is the easiest thing in the world if you already have a system installed. Should be like $20-30 in parts (not including battery) to install.
16V can be obtained by adjustable voltage regulator on your ALT. Unless you have a very good knowledge of the car's electrical system, i would not get one.
Caps in your amp help steady the voltage to your amp's power supply, they soften the spikes so that the amp has a more regulated (ie less fluctuations) input voltage. A larger cap outside will assist in this as well. This will keep the power supply operating more efficiently and in turn run the amp cooler. In theory this leads to a cleaner output as well. Some folks dont understand that and claim a cap is a burden - how something that does not consume or cause loss, is a burden is beyond me...... those people dont quite get the whole picture.
Wow truly sticking to the "Let's set the record straight" mood and mentality. Thanks.
You asked for, you got it.....(toyota)
Young children's hearing is so much more sensitive than ours and so much more susceptible to damage from loud noises. 
Do NOT play your system like that while driving around. If you're in a controled environment like at a show or something and people are stupid enough to sit in the car "for a moment" and risk their own hearing, so be it.