I pulled out my cabin filter to clean it when installing heated seats. Didn't get around to reinstalling it or the cabin filter cover. Drove the next day to my office with the AC recirc flap open. REALLY could hear the SC and intake. Definatelly would not drive around like this for an extended period of time, because it's super loud and annoying, but is very intresting for a day to hear the SC sound and sucking throttle body in a variety of conditions. If you are changing your cabin filter, give it a try!

 

'Sounds like fun. And it sounds like something I used to do with my old '73 VW bus. '73 was the very first year that VW put an access hatch to the engine inside the bus, directly over the engine. I never drove around with it opened up but then I put a highly modified, semi-race 2.0+ liter Porsche motor in the bus and discovered that it was super fun to leave the cover off and have that motor echoing throughout the bus.