Alright i have a fosgate p8002 and a p4004 amp in the trunk.. i have a 1 farad capacitor and the headlights still dim a lot.. (even when im driving) how much of an upgrade to the capacitor do i need...

 

just get another 1 farad cap. the only reason u would need something bigger is if ur running something insane like 2 or 3 JL 1000/1 with a couple smaller amps for speakers like my friend. he needed a 15 farad cap, haha. also consider upgrading battery if u havent done that already. but get another 1 farad cap and u should be fine.

 

A good rule of thumb is one farad per 1000 watts. I don’t think adding another cap is going to help with your light problems. I have a DEI 50 farad cap and still have problems with my lights dimming. As mentioned above you need to upgrade the electrical system to eliminate all of that such at the alternator/battery...

 

get a thicker awg of wire, some ppl run 3k watt rms systems with no caps but with 0 awg wire. if thats not the problem your altenator isnt producing enough amps, an se altenator should put out atleast 110 amps

 

Didn't want to start another thread with a very similar question. I was wondering if I will likely need a capacitor when I'm running around 600-700 watts all around? Is that too much for our cars? I have a new battery and recently installed a G35's alternator... going from 110amps to 125amps if that matters.

 

For "ionpcs" a 1 Farad cap will work just fine (with decent B+ & ground wire).
For "f550maranello2" add one more 1 Farad cap (with decent B+ & ground wire).
For both of you, make sure you have a really good ground back there in the trunk. Then make sure you have upgraded your ground from the body to the battery and the engine to the battery. A 1/0 B+ wire and a cap is useless with a 6ga. factory ground wire. For those opposed to caps, I don't want to hear it

 

IMHO, caps are a complete waste of cash. Upgrade your amp wire to 0 gauge, then the BIG 3, then...if all else fails...get a high output alt. Caps = teh waste of money.