Thanks for the replies. I am not so afraid of the amount of air that will go into the engine, but rather more about the purity of the air. The air in the airbox of Tenere is already post-filtered, which means it is clean. In my case, the air potentially entering through the holes is not filtered. I am mostly concerned about the dust or the water (in case of crossing a stream or a small river) that might be sucked up into the airbox. If, as SingleMinded writes, Ten sucks up up to 1500 L of air per minute, I could easily imagine water filling the airbox through the bottom hole...