dealer rarely try the car, they just look the inside and outside of the car and rarely the engine but the vw dealer who I did order my polo took my car for a low price cos it a classify as a gti and say it could have been difficult to resale vut they lucky for same sold it quickly and after they ask me for the original spare part(airbox, exhaust) told them I have a look at it never did as I sold the spare part and thats because they didn't even check the engine bay as long as the car is clean outside then u wont any problems