^^^^
Yes, the filter is perhaps the most important component in an Air Intake system.
I'd have to conduct quite scientific tests to tell you what any improvements are, and you know what the placebo effects are!
My Carbonio intake came with a PiperCross panel filter and someone I know with a Mk5 GTI, who is a highly qualified engineer and whose opinion I respect, told me ITG were the best. 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.
Don't forget that the VW standard filter gets thrown away and replaced every ?,000 miles when servicing - What does that tell you?
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.
It's also MAF-friendly! And probably more benefit to a remapped car.
If you plan on keeping your car, as I do, then it'll quickly pay for itself by not needing to replace it - 60 squid well spent imo.
