Attention Sydney, NSW residents Want a free K&N air filter? K&N's Research and Development teams may need your vehicle for fit checking of K&N air filters. We are looking for Australian vehicles to fit check K&N air filters to confirm our catalogue listings. It does not take long – we just need to check OE numbers from your VIN number and then document the installation of the K&N air filter into the standard OE airbox. After a successful fit check, we will leave the K&N filter with you as our thanks for helping us.