Recently I had a capacitor installed into my car to power my subs.

I decided to put some neon in the trunk of my car. When I hooked the + and grnd upto the same on the sub terminal, the neon always remains on.

I'm thinking that it'* just drawing power from the cap, but I'm worried that this might do damage, and/or drain the battery of my car.

Anyone know for sure?

There is always the potential for power from the main power lead to an amp because it is hooked up directly and/or through cap to the battery. The amp and the cap have remote power leads that turn them on with the radio. So hooking something up to the main power lead and ground, it will have constant power. If you hooked up a switch in the lead between amp and neon, or used the remote power lead for the neon, it might work more to your liking. I don't know if the remote power lead is enough to power the light, however.

Hehe hers an idea.. Tap into your power intenna power source wire and connect it to the neon and the intenna but remember to increase the amp fuse in the fuse holder or you might blow it with too much draw.... Your neon will turn on and off with your radio and wont drain your cap or your bat.

Good idea russianpolarbear, except my power antenna only goes up when I'm listeing to the radio... which is never.... the mp3s get the best of me.

Right now the setup is this....
battery -> cap
cap -> amps
tapping the pos/grnd on the mono amp for neon

It'* either going to drain the cap, or drain the battery & cap.
I'd rather not find out the hardway... hehe

The antennea should be up whenever the radio is on.

My antenna does the same thing. With the stock head unit the antenna would go up as soon as the power came on. Now it only goes up when I switch to the radio.
You might be able to hook the power to the remote wire and just ground the neon normally, neons use practically no power. I'm not sure that will work.

When I said radio, i meant the whole stereo in general. I didn't know that with an aftermarket head unit, the antennea only came up only when you are listening to actual radio.

I got the same result after installing an aftermarket deck,hurtin *** antenna only comes up when i switch to radio which is very rare

Yeah you could just get a low amp relay hook it to your radio remote and have it trigget the 12v feed from the cap to the neon... How about that

i learned the hard way NEVER EVER EVER hook anything up to your amplifier to power it its very easy for terminals to blow out, also the circuttry in the amplifier might not be able to handle the extra draw, depeneding on the neon it can draw up to 2 amps, which might not seem to be a lot, however it can add up.. i would personally reccomend some form of fused distribution block just before your amp, then take one positive out of that run it to a "master" switch, then you can daisy chain other switches off the master one (provided you pick up a 30amp or higher switch) and then have full control of your neons, and one main "cop stopper" switch.. just my .02