I've noticed the hissing in my accord. It sounds like a vacuum. I got one of the AEM CAIs and since I live down in Miami, FL I cut the pipe right before it goes down into the bumper. We get too much rain down here during the rain season and hydrolocking is a pain. Ive been through it. I'll just use a rubber sleeve and extend the intake once again with dryer weather. AEM does offer a bypass to prevent this, but installing the bypass kind of ruins the point of installing the CAI because the intake now sucks in some hot hair from near the engine. I have my filter set right above the opening where the pipe drops down, and I removed my wheel well, so Its getting a good amount of cool air right where it's at. Plus I don't have to worry too much about driving through a puddle or two once in a while. A friend of mine installed a SR in a Ford and we also noticed the same vacuum sound. Its just the engine breathing freely. Plus any female that would dare say something like that about my baby would end up walking.