Stereos for Idiots
 

So I do an enjoy a nice home theater system or boat audio system, but I must confess, I know little to nothing about building or installing one.

That being said, and for sake of saving some money, how hard would it be for me to add tower speakers to my existing system? Right now I just have one amp that runs my JL 10 sub and interior speakers and have a decent head unit. I have a dual battery setup as well.

I know the Illusion X tower (own a '05 Malibu) has a prewired tower. Is this wire guage sufficient for a pair of wetsounds? I assume I would just need to add one dedicated amp and possibly something like the wetsounds EQ for volume control.

So I guess what I'm asking is if this installation is doable for somebody with little to no experience doing audio installations? I not looking to do anything too fancy.

The wire in the tower should be fine for a pair of speakers. What ones are you thinking of? The bad boys are the Rev10s but there are also other choices.
You definitely want to get another amp for it to power them. Depending on what speaker you go for, you want to get an amp that puts out at least the same, if not more RMS than the speakers' RMS rating to get the most out of them. No one likes an underpowered speaker that starts clipping at high volumes.
Get the Wetsounds WS420 (or it's variants, SQ or BT) to be able to control the zones and tune the channels. It only needs one pair of RCAs from the head unit and it controls the signal going to power your in boats, towers, and sub. It is an awesome EQ and makes everything work so much nicer.
It is very doable as a DIY, especially if you already have an amp installed.

If you have big enough wire going to your existing amp you can get a distribution block/y adapter for it and split off between the two amps, you can also do this with the remote wire. Make sure it has it's own ground though.
You can possibly steal a pair of RCAs you have going to your amp since the wetsounds just uses 1 pair of RCAs for each zone, not 2 for front/rear. You would just use 2 y adapters for the front/rear of your 5 channel (i'm assuming it's a 5 channel) your amp also may have an option to internally use both.
To install the wetsounds you can splice off the power wires going to your head unit since you are going to be mounting it somewhat close anyway, if not right next to it.

Aside from that, if it's prewired and you already have speaker leads where your amp is, then mount the speakers with tower clamps, angled up a little bit so they are poined out behind the boat when factoring in some bow rise.
Hooking up all the components isn't too hard in itself, it just takes a little time. It is totally doable by yourself. The main thing is take your time and pay attention to where everything goes.

I know a lot of people here on the forums, myself included will be happy to help you out with any advice if you get stuck.

Unless you go ape feces with power and speakers light gauge wire is fine on the speaker side. You're dealing with alternating current once you get on the output/speaker side of the amps so it doesn't require a very large conductor.

Think about the wire size running your refrigerator at home. It's a high current draw AC appliance and it probably only has 12 gauge or maybe even 14 gauge wire running to it and it's likely also a 30' or longer run from the breaker panel. Then go look at your battery cables in your car or boat that run to ground and the starter solenoid. That's a high current DC load and the cable run is probably only a couple of feet but note how much heavier gauge the wire is (Usually 4 gauge or fatter).

It is still DC to your speakers, there is no AC

What???
Music is transient/AC in nature.
All autoformers are multitap transformers plus impedance correcting devices are transformers and transformers don't pass DC.

The wire size difference in your home is due to being 110 volt power source instead of 12 volt like in a car or boat.

Check your PM