With all the electronic systems and computer monitoring and whatnot, was wondering if there is any risk to putting in a slightly larger battery into a vehicle if it fits?

For that matter, is there an advantage if you aren't running a bunch of extra electrical accessories?

About to be time to replace my battery, and from what I can tell I can adjust the battery box to fit the next size up battery that's a little longer. Same price, but get an additional 80 CCA, and 20 minutes reserve capacity. My assumption is as long as it's the same 12V battery it should charge just fine, and could potentially extend the life of the battery - at the very least make it less likely to have a random dead battery.

Before doing this I would check to see if the retailer you plan to purchase the battery from will warranty the battery in an application that it is not intended for. I suspect some retailers will use that as a reason to void the warranty. Even with most places going to a 3 year warranty, I still typically get 2 batteries for the price of one or at least a pro-rated price on the second one.

Yes, it's pretty common for modified vehicles running refrigerators, solar, aftermarket lights, winches, wenches, etc.

If you google your vehicle and "larger replacement battery" I'm betting someone has already done the research.

...or you can go wild. I moved my Tacoma's battery from the front fender to behind the back seat with heavy gauge wire, and went with a much larger battery.

A friend of mine put one of these systems with 2 full size batteries in his Jeep Wrangler JLU.

What kind of car?

I usually replace with a larger size but you need to code the vehicle for the next size up

Chevy Malibu

I don't think that rattle trap can handle the sound system you have in mind.