Ok, so in the process of fitting my 034 shifter cable bushings today, I removed the airbox to gain access and noticed that the hose from the airbox to turbo inlet was quite dusty on the inside. I have Leyo silicone hose to racingline inlet. Being on the clean side of the filter this should be clean with maybe slight trace of oil. On inspecting the airbox I found usual flies, leaves etc on dirty side but traces of the same dust around clean side sealing edge of the filter element. I was running a K&N but swapped it for a Pipercross a couple of months ago after reading about K&Ns being over oiled and it being sucked out under hard power, potentially damaging sensors etc etc. Never gave it a thought at the time as it was the correct filter for the car but now I've compared the K&N to the Pipercross, there is 1mm maybe 1.5mm difference in the thickness of the rubber edge of the filter. I firmly believe engine compartment air was being sucked in past the seal, unfiltered, due to the lid not compressing the seal enough and yes the lid and all hoses were firmly secured. Needless to say I've cleaned it all up and refitted the K&N, just hope it hasn't done any damage to the turbo, time will tell. Posting so anyone running aftermarket filter in OE box is aware of the potential issue and maybe take the opportunity to have a peak at yours, Oh and I would advise not to buy a Pipercross, it doesn't seem to fit properly,!