Racing Filter detected by dealership despite replacing it with OEM filter

[SaifQ]

Hey guys,

I drive a 2017 440i coupe with a stage 1 tune. I recently equipped the car with a BMS filter for enhanced sound and power, and wow was it worth it. When it was time for my service, i replaced the filter with the original OEM one to maintain my warranty. After receiving the car, they told me they know about the filter and made me sign a warning letter saying if they found such parts installed again it would void the warranty. I obviously denied it but they forced me to sign it anyway.

Is there some way i could install it without them knowing i did?

Thanks!

[chikinhed]

You may have better luck installing a dry, non oiled, filter. Oiled filters will leave a residue in the intake and can contaminate MAFs.