Probably been posted before, But here are some hilarious Mighty Car Mods where they mythbust some common mods for cars. Yes their cars are Japanese imports but hey.
CAIs Mythbusted
http://youtu.be/gCi2yo4UqPI
POD Filters Mythbusted
http://youtu.be/PAIxeQUSg-Q
Blow Off Valves Mythbusted
http://youtu.be/Z_fG_b65WiU
Electric Superchargers Mythbusted - Particularly funny.
http://youtu.be/cbGWgvJN1_8
Not too sure how to embed vids sorry.