Is it like a whislting noise when u go through like 4k?? If so theyll take the clmap off put some sealent round it, well depends where its blowing from, but thing is u cant really drive the car for that long afterwards. Mine was fine then it come back again, got it sealed again, and made the mistake of not letting it set, and the thing sound,s bad!!!! For a new cat from reno there £910.