I have had my share of problems also with the ITG open filter. 2 years ago I bought it for my Leon Cupra (k04) and my driveability and mpg suffered like have been discussed here. I complained about this to ITG, but they wouldnt want to listen to me
When the air flow meter is installed in their MAF section, the meter doesnt even sit on the dead center of the pipe like it does with original airbox. ITG just commented that it seems to work fine like this.. yeah right. Air flow meter even blocks more air now going to the turbo so I fail to see their logic in designing it like this. Maybe they have fixed this? Its been about 2 years now since I bought mine.
Well I ended up twisting the MAF section around to a different angle to see if the air flows are different in other location of the pipe, this made a considerable change how to how the car behaved. The low end grunt got back and mpg was almost normal. I was happy enough with it in the end, even with its design flaw.
Im currently driving a mkv GTI and fitted the same intake. From the start if has worked a lot better then with Leon. All I did was clean and reoil the filter (I didnt even use ITG stuff). Last time I checked my fuel trims, they were both almost zero. Stock airbox was at about -3 IIRC, so very close and I havent really noticed any problems in driveablity or mpg, only more power and sound. With precat delete I seem to be getting quite good mileage combined with Revo stage 2.
