Open such as Pumaspeed and Dreamscience sell which give a better noise
Or Closed such as Autospecialists and Graham Goode Racing sell which as it suggests the filter is closed inside a case with a pipe leading into it which I believe connects to the original ducting for the standard airbox at the front grill. This type of filter is very quiet, will give little more noise than a standard airbox.
People will recommend whatever they have on their own car and say that's the best system.
I've had both the Dreamscience and Pumaspeed system on my car.