You're not gonna notice much, if anything, in terms of loudness. A hundred watts isn't going to be noticeable at the power level. But, it is moderately efficient, and they do tend to be underrated. So you'll probably notice less power consumption, and it may run cooler. And, if you step down to 1 ohm in the future, or .5 ohm, you'll have a ton more power on tap.
But you should definitely get your big 3 done. It shouldn't cost any more than $30 or $40, it's super easy to do, and drastically improves the electrical foundation for your car. All it can do is help, and allow more power to flow.