ive got a 2gauge earth + all 2 gauge wiring + platinum distribution/fuse box + a 2.4 farad cap + expensive 700ish cca battery brand new
i still get lights dimming a bit when turned up high why would that be
The only thing I can point to would be the amps drawing lots of power due to being cheap and inefficent

what amps are you using

crappy Boss amps ive got 2
they put out "stated" 250wrms to each sub but knowing the amps s**t I set the gains using a multimeter to give out around 200w rms to each sub
then the other amp supplies power to the rears and fronts

still even with those amps with 2gauge wireing and a capacitor it shouldnt dim lights should it??

Try using a multimeter and see how many volts you are getting with car running and no accessories and then headlights and then with the sound system turned on .That will be volts at the battery and volts at the alternator battery positive.If you get more than 1/2 a volt difference between these 2 points then you will need to put a heavy duty wire to compensate.DO all the tests at idle and at 2...2 1/2 thousand revs and make sure the battery is fully charged ,it may be new but it may have sat on the shelf for a while.Keep in touch Kevman....oh yeah learn Ohm's law.Don't leave home without it

the battery isnt completly new its been in the car for a bit over a month
as for upgrading a wire which one exactly??
I have the stock earth wire and a 2gauge one going to the car off of the battery

I havnt done the voltages at different rpm but it stays the same with the sound system on untill i crank it right up then it drops about .5v

na mate it wouldnt be the gear because im running all alpine gear and my lights still dim a fair bit but thats in 8guage wire and with no capacitor or anything getting a capacitor within the next week tho but why is it such a problem is it only your interior lights dimming or is it your head lights and cluster lights etc ??

you will probs find you alpine amps will actually draw LESS current due to being more efficent

as for the dimming its not major, the interior lights dim a bit and the headlights but not the cluster due to being modified with led's

having said that it only happens when turned up greater than about 80% which is pretty fn loud and i dont listen to it that loud whilst driving by far

ahh ok that makes sense
as its the alternator that supplies the extra few volts while the cars running and the cable between the alternator is still small that extra voltage is prone to drop before the battery can make up for it.

I may look into a new alternator too.

I have zero guage.... a 1 farad cap, upgraded earth links all over and 600 CCA battery and my lights still flash to the beat... Not as bad as before I got the cap and earths.. but still there abit.

If you use class D amps (like alpine PDX series) you'll use less power for a given rating but with Boss type amps.. you should consider yourself lucky you can even hear it over the engine noise. (long ago I worked at strathfield)

what do u mean hear it over the engine noise, what due to the strain on the alternator
I will get decent class d amps and i was looking at focal fronts but at the moment id rather spend the money on performance/handling/speed as the sound system is still F'ING loud and reasonable quality

I mean that boss amps have a tendency to pick up any engine electrical noise and amplify it...

grunty amps though.

actually ive had no engine noise problems at all

maybe they are better now than they once were...

I have a boss amp here that I was given and I took it out because it sounded like I was turbo charged whenever the volume was low.,

haha lol
what rca's were you running
ive made sure im using good ones run on the opposite side of the car to the power wires

yeah... I was a fitter for a long time..so all the usual stuff was done.. good rca's... good earthing, no ground loops etc... but only thing that fixed it was a different amp...may have been a dry joint or something in the amp itself.

yeah maybe or they've just improved their build quality