Hog wash on the power gains.
Few things to gain from air filters but nothing to get too exited about. One is the ability to be able to rewash some of them which is great for offroaders. Secondly, although rare on todays modern cars, you might be able to get away with a colder air intake than stock, but our Touareg's intake does rectify that anyways. Then there is sound, as some stock systems to use baffles in the plumbing, to quiet down the intake sound(NVH). Both the Vr6's and V8's sound great when you WOT it with baffle less intakes.
There was an aftermarket intake that I used to use on my BMW, and I really did love it! It improved sound which was what I seeked, and also sucked in cold air, just like the stock system. This guy has been making these for a while and I love them, here is the link. Welcome to PRM Racing - Jet Stream Intake System
Unfortunately no Touareg application, although he does make universal kits, which probably still wouldn't fit anyways(I THINK :-k), although I am tempted to call.
Being someone myself who likes to tinker around and experiment, as far as our T-Reg is concerned, and ONLY FOR THE SAKE OF SOUND, the idea of adding 2 of those PRM intake capsules on my V8, does sound enticing to the 18 year old in me