technical explanation:
a speaker box system has an overall damping factor known as qtc. in layman's terms, qtc is the "air cushion" or "spring" that dampens speaker movement. the less damping (smaller box) will result to emphasizing bass impact at the speaker's resonant frequency, but with less deep bass. the more damping (larger box) will result to extended deep bass, but less bass impact.
so what does this mean to you?
making a hole in a closed system will make the cabinet effectively larger, more damped, creating what is called an infinite baffle or freeair system... resulting into deeper bass response, but less punchy bass. less impact more "ugong". if you're a powerchord chug-chug kind of guy, you will not like this. but if you play clean (jazz-etc) you may like this because the sound is deeper, and and bass notes sound more even (albeit weaker).
if i were you, if the speakers and cabinet are designed to be closed, i'd keep it closed. the guitar's lowest note in standard tuning is ~80hz. what you gain in deep bass below frequency is irrelevant. the only time it would be relevant is if you play in lower tuning, and you are willing to compromise impact in order to get ugong.
