I'm going to be installing an 800 watt amp that will be powering 2 12" subs with 400 watts each. Am I going to need a cap for this? I read on a couple of sites that it is a good idea. Also, a friend of mine said it could be a pain in the royal A$$ to install. Do you guys recommend installing one in a system like mine and have you ever ran into any problems installing one? Thanks.

Personally, I'd use a couple farad caps if you're gonna be cranking out that much power. If you have the high-output alternator, it'll still have weaks points when your bass hits hard and it might have trouble supplying that many amps, let'* say, at idle (especially if your heater is on, maybe your headlights, etc.). It'* also a good idea because then you won't notice dimming of lights/equiptment in your car when it hits hard (or it won't be as acute). They're about the easiest thing to install, too, and I've never had a problem with them, ever. Too bad they're so damn expensive.

I think in general, caps make the biggest difference (improvement) in sound when people use wire that is just a tid bit too small of a guage for the battery to amp connection. This is definitely not recomended to fix that problem (always run wire that is the proper size, or even a smaller guage), but it does illustrate where caps "appear" to make a huge difference.

Caps can always be added later, so I'd wire up your subs with a 6 guage wire and see how it works. Then, if you experience the dimming, or they don't hit quite as hard, and it sounds like they're not getting enough juice, add a cap, and if that works better but not quite perfect, add another cap (connect in parallel with each other).

a cap is very very easy to install... you can pick one up at wal mart for $40 (one farad = 1,000 watts)... i wouldnt necessarily get a cap right away, try it without one first, see how it works... use 4 gauge wiring, you can buy a kit with rca'*, power, ground and a dist. box for like $30...

Definately get a cap.... I've run w/ and w/o a cap.... a cap makes a difference... well worth the $$$.

Well after reading what you guys wrote, I think I am going to go ahead and buy a cap. I'm buying most of my stuff from sounddomain.com and they have a 1 Farad with a digital monitor for $105. I'll probably just go with that one. We'll see how my car reacts with it installed. Hopefully, everything will be cool.

Another question for you...am I going to have to buy a more powerful alternator? I hope not but you guys know a lot more about this stuff than I do so I'd like to know what you think. Thanks again.

you can but one from wal-mart for half price

A digital cap is a good choice, you can find them maybe cheepier on ebay if you look.

As for Alternator, you should be fine. So far mine has lasted me and I'm putting some serious strain on it. Not worried about it for now, maybe before next winter I'll upgrade my alt, no idea on what kind I'll get. Probably install it with my local GP buddy.

Here'* my 5 farad that I got for 220 new at a store, my stereo shop didn't have any in stock when my stuff was getting installed, they told me to go to a rival stereo shop and tell them that they would sell it to me for 240, they beat the price and I won. I think mine list retail for 350 ish.

Dont forget caps are rated in RMS power not peak. For a regular cap it is easy to install as well as charging it.

A cap is a cap, go with the cheapest brand name with warranty you can find. Digital doesn't make any difference. Those digital readouts are more of a marketing gimmick than anything. And if I was you, I'd get a new alternator, rated for 160 or more. Then, you have it on hand when your current one dies, cause if you run that system really loud often, it will die :(

Always nice to have the backup ready

Caps don't help with bad power systems, they only keep your lights nice.