So, I've said it before, and I'll say it again.
I personally think (take this for what its worth) that you need to just be worried about getting in your car and having it start every time, and get you where you're going. Picking up a couple buddies and heading to the movies, not swapping motors. Being the age you are, and this being your first car, nothing else is important really. You are also not affording this car on your own.
A new battery definitely falls in the category of al excellent idea, but doing things like moving your battery to your trunk, not suck a good idea.
You have to take a step back and also realize that you're driving a 11 year old car that in the end isn't worth doing things like full car paint jobs and Red Top batteries relocated to the trunk. You would be throwing money at this car (that you don't have) that you will NEVER get back out of it. Once you are out of school, and get to the self sufficient point where you can flush money down the drain on your car like everyone else. Then go wild.
Drive the tires off this thing. Get yourself through high school and college. If you still have it and love it then, toss some money at it. You haven't yet, but you WILL stuff this car in a snow banking. Don't worry you don't have much into it. Your dumbass friend WILL back into it with his first car. Don't worry you don't have much into it. You WILL spill an entire big gulp on the passenger seat be accident. Don't worry you don't have much into it. Get where I'm going with this.
I had the oppertunity to buy my first vehicle from my dad. I had to pay for it on my own, but it allowed me to get into a low miles reliable vehicle for much less then it was worth. (Thanks dad). I did nothing but drive the crap out of it through high school and commuted to college. You know what, when I got out of school, I still have a low miles truck that I loved. But it had a bent bumper from sliding off the road, dings dents and scratches. I went out and took out a small personal loan on my own, and bought some wheels and got a paint job on the truck, and lowered it. Then I made it my own.
/rant/advice
As for the battery just go buy yourself a decent middle grade battery. Chances are the battery you have now has lasted 11years. The next one you buy will last longer then you need as long as you don't kill it by leaving a dome light on or something. Put it in the stock location, and enjoy!
