I did a little ghetto-modding today. I took out my stock airbox, got my drill out, and put a bunch of holes in the lower half of it on the fender-side. I know what you're probably thinking. "Stupid." "Ricey." "Doesn't do anything."
Well, you're wrong. It's not a drastic improvement. It most likely didn't even give me 1whp. But what it did do was make the intake a little louder, and give me much better throttle response. I took it on a little test drive afterward, and if I snapped the throttle from cruising to wide open, the car no longer bucked and hesitated. Not bad for a mod that didn't cost me a dime.
I didn't take any pictures while I was doing it, since I was dirty, and you can't see it installed (it's under the upper intake). So I found someone else's picture of basically the same think I did. Only the picture is off a Mk4.