I put in my amp and subs in my 03 coupe, about a week ago, and when the subs are on, the car idles lower than normal, sometimes as low as 400 RPM's, and the subs sometimes don't hit, they are silent when they should hit. The battery that i have doesn't look very good(i just bought the car). I figured the car would be able to handle the amp and subs that i have, but I think i will either need to put an optimum battery in, or put a capacitor in. What do you guys think?

 

my friend you need a capacitor...100% sure!!

 

how many watts is the amp pushing?

 

Are capacitors easy to install? I think i might need one too. (sorry if im thread jacking)

 

^caps are easy to install. To the OP defainately change your battery and invest in a capacitor ASAP. Also check your wiring and make sure the speakers are wired correctly to the amp.

 

How many watts are you running?

You can probably forget about the cap and just change your battery.

 

Did you connect everything yourself? How did you wire it and what equipment do you have?

 

how big is your GROUND Cable?? did you do it right?
to help your questions.. be more specific

AMP = how many watts?
Sub = ohms, watts???
how many speakers you running etc..etc..

 

battery or a bigger alternator.capacitor will help but in the long run depending on how much power you are pushing you will need to upgrade.