Pros: You will get more out of your amps (if they can handle 16v), your output will increase from the manufacturers specs. If properly done, you could have much more consistency in the voltage (no fluctuations,etc...).
Cons: Not so cheap to do. You may be looking at upgrading your entire electrical system and upgrading equipment to do this.
Most people that do this are serious SPL competitors that are literally squeezing every ounce out of their systems. However, most of these people also have sponsors who pay to replace blown gear. Keep that in mind too. I looked at upgrading my system a number or years ago and was looking at nearly $4k to do so.
Details: Higher cranking batter (or batteries), Upgraded alternator, larger grounding cables for battery and alternator, larger guage wire from battery (or batteries) to amps, possibly buying new amps, adding capacitors and/or power regulators, etc... the list goes on and on.