Has anyone done this mod??

Smoothed airbox is what you want.

Seems to be more popular among the MK1 TT boys 'n' girls, shove 3"feed into the airbox

Had a smoothed one on my st220

Think the tt guys call it wak box mod or something, I smoothed my airbox.

I done it combined with de finning and 3" ducting . check out the details in the Skoda Octavia the technical guide section

Here it is

http://www.briskoda.net/forums/index.php?/topic/181301-How-To:-Airbox-Mod-and-3"-Pipping

How To: Airbox Mod and 3" Pipping