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People have certainly taken hole saws to the original cover, and I recall seeing a carbon fiber air filter cover with large holes molded in it from some aftermarket parts supplier. I don't know if it does any good. Air flow through the CIS system already seems pretty f'ed up. Hard to imagine that the original air filter cover makes it any worse. The design is likely more focused on preventing water intrusion than on performance, a feature you will eliminate if you remove the cover or start punching large holes in it. Not a problem if you don't drive in the rain.