i doubt very much it wil be the filter. i had FR before my R, and im telling ya, the cars behind were driving through my smoke when i remapped it to 190bhp. it is really bad, and i hated it. be careful though with the remap on the diesel, my car did 18k miles and the clutch cudnt handle the torque it was pushing out, plus my turbo went bust so had to get a new one, i dont think the diesels like a remap, so just keep look out