Had this aem cai for years that i bought used but never saw this hole til the other day. Its small, 1/4" or less cuz theres a rubber grommet also with a hole through it. This is NOT the breather hole cuz i have that line hooked up to the valve cover. Its located directly underneath a few inches from the throttle body. The only info i found on a search was people talking about breathers. Anyone know what this is for or might have been done by the previous owner for? A friend suggested it could be to help relieve pressure in case the filter gets a ton of water or maybe it was used for a sensor before. Its pretty small for a sensor i think. Thought id ask before i plug it up entirely. Meant to snap a picture before i bolted it back in but oh well.