My Carbonio intake came with a PiperCross panel filter but ITG have an excellent reputation.
From whom?
The ITG filter is certainly of very robust multilayered construction and fits the 'box' very tightly, so sealing is good - Better quality than the PiperCross which in turn is much better than the standard 'paper' panel. Extremely low maintenance was also a factor in my decision - No additional oiling is ever needed and just an occasional dust off. Also a lifetime warranty.
K&N also have a lifetime warranty to, but I wouldn't even fit one of them to my lawn mower - never mind a modern car with a MAF! 
Don't forget that the VW standard filter gets thrown away and replaced every ?,000 miles when servicing - What does that tell you?
I don't get your point. The 'standard' VW oil filter gets thrown away on a routine basis, as does the engine oil, the DSG oil, and the DSG oil filter. So, by the simple fact that the OEM paper air filter actually collects and holds any contaminents, ready to be disposed of in a routine manner (and therefore quantifiable) - has got to be far more efficient at filtration than something which never, ever needs changing.
So, by using that logic, how would you feel if you got a fone call on Monday morning, either from your highly trusted VW dealer, or JKM, VWR, Awesome - or whoever. And the phone call went something like "Good morning Mr RedRobin - I am foning to tell you that we will change your engine oil, and refill it with oil that has a lifetime warranty, and never needs changing. It is guaranteed for 250k miles - and your engine will see noticeable gains in performance, reliability, emissions" . . . . . I don't know how you would react, but my answer would be a brief two-word reply, begining in "F" and ending in "F" - quickly followed by ending the call. 
Air filters are designed to have two specific primary functions - and whilst one is a trade-off from the other, and vice versa - both those primary functions are pretty vital on a road car engine.
The ITG Pro-filter utilizes the same three layer reticulated polyester foam used on the MAXOGEN air filters. Unlike some of the competition, ITG filters have a massive dust load-up tolerance, which is the ability to absorb a large amount of dust without reducing air flow capacity. With the standard K03 turbo I wouldn't like to say that any performance gains are appreciable without proper scientific testing. However, the manufacturers claim about +2 bhp is possible.
2 bhp is nothing. Completely insignificant. Greater changes could be seen from changing a dirty OEM filter for a new OEM filter. OK, granted, a new OEM filter won't give any increases over and above the manufacturers standard power outputs - but it will provide considerably more filtration protection compared any 'foam' or cotton types of filters.
It's also MAF-friendly!
How can you say that? It is an 'oiled' filter, and even if you do 'clean' most of the oil off, some will still find its way onto the MAF.
And what about the TURBO? All that unfiltered air goes through the turbo - and as you well know - fcuk up a turbo (for whatever reason), and they certainly aint cheap. The cheap cost of £50, along with the "extra 2bhp" (whooo hooo!) will be long forgotten when you have to lash out £1500 for a new turbo. 
And probably more benefit to a remapped car.
Remapping alone wont be aided by just a freer flowing air filter. How can it? Physics provides the correct answers. A 'freer flowing' air filter will only provide noticeable benefits if, and only if other associated changes are made throughout the 'air circuit' of the 'engine'. For the GTI, that would mean: exhaust system, cats, and intercoolers. So, on that theme, a Milltek zorst, and/or an uprated intercooler will provide far greater improvements compared to any filter (even a completely removed filter) - but won't jeopardise the reliability of the engine, MAF or turbo.
If you plan on keeping your car, as I do, then it'll quickly pay for itself by not needing to replace it - 50 squid well spent imo.
Sorry, disagree. Non-standard air filters must be one of the least sensible mods to do on a road car! OK, an aftermarket may be very cheap in the overall scheme of modifications - but its 'fcukability factor' must be one of the highest!
Totally Agree with TT's Comments. The paper filter is sacrificial, and bloody good at its job.
The K+N etc brigade are all oiled, and this will find its way onto the thermo strip of the MAF, get burnt on, and mess the output signals of the MAF. When you can remove the paper filter after 10K miles and replace for the price of 2 pints it is good enough for me.
After 10-15K, how do you clean a Aftermarket filter? and how clean can you get it? But as they sy ETTO.
I believe the MAF on VW's is a Hot wire type............
http://en.wikipedia.org/wiki/Mass_airflow_sensor
