OK here is the story on the AEM air bypass valve. Mods we should make an archive on this if it has not been done already...this has been posted often.

The air bypass valve has been proven to stop the flow of water up the intake only when the filter has been completely submerged in water. To my knowledge AEM has not published any test results when water is splashed on the filter as to whether or not the bypass valve works.

Also to my knowledge, AEM has not published any dyno sheets comparing the intake with the bypass valve and without it. There is no proof that the bypass valve reduces the increases in HP & TQ over an intake without it. Conventional wisdom here does sugest that the valve would decrease performance because the smooth contours of the intake are now interupted by the bypass valve thus causing turbulance in the intake. However this has yet to be prooven.

Rule of thumb with a CAI...be carefull when driving in the rain/snow regardless of whether or not you have the bypass valve installed or not. I would also take it easy over puddles. For those that do have the bypass valve installed you may drive your car through small rivers, ravine's, creeks, and large puddles of 1' or more (depending on suspension drop) and feel safe that AEM has successfully tested their air bypass valve and that you will not suck water up into your engine. So unless you plan on driving in any of the above conditions you may not need the air bybass valve.

My recommendation if sucking up water is that important to you...go with Comptech...they guarantee the Ice Box will not suck up water in any conditions.