The only real way to tell for sure is by plugging the car into Vag-Com and checking the fuel trims and doing some logs. If the maf housing is too big for instance then this would cause the maf to under-read resulting in the car running lean, which the ecu will correct to a certain extent. You may experience misfires and extreme timing pull if the ecu is pushed passed it ability to correct the fueling. With that said, i wouldn't worry if you haven't had any running issues. These cars are very clever when it comes to safe guarding themselves.