This was done on a the 1.8t, and might be a little different on the Tdi's, but along the same lines.
First off I removed the headlight, as this gave more access to the area you need to work with, and i was replacing my lights anyway with Xenons.
I tried looking for a drill peace that cut a round 1 half inch hole as this would be better, but ended up using a 8mm drill bit. best to mark the area on the box you are going to cut, with tipex or small paint brush. cut the hole to a smoother shape with a good sharp knife.
This method is not removing the airbox (the quick way if it's cold
)
Flexable plastic pipe about 2" bore....
drill holes in the area where you want your pipe to go, but don't go to high up on the bottom part of your airbox, as you need to cut/drill below where your filter is inside.
once you have made a good enough job of making your holes, remove the bottom drivers side grill, to see where you want your pipe to run too. It's tight in there so i placed mine going around the condensor (round tube shape thing) you can strap tie them not to move, but you'll find they won't move around much in there anyway.
You'll be better tring to place the pipes where you want them to go before you push them tight into the holes in the airbox silicon seal it around, or gaffa tape, just so no air gets in any small gaps where you cut, and if your happy with the way I've done it, then ALL GOOD!
Just put your car back together, and thats it, but if you do this mod then do it in better weather than i did, as it was very cold!
Got the xenons on while i was at it! go for a test run and see if theres a differance!
