I know this is an old subject talked about many times. But maybe there is a new manufaturer out there I haven't heard about. Few years ago I bought the K & N cold air intake. Have not been satisfied with it lately. The tubes got worn and had to use wire to hold it in place. Looking to buy one now that is fully inclosed (box) and one that might have the scoop option in the bottom for my 2004 CTD. This leaves out a few manufactors but was wondering if some of you may have other ideas. Maybe even building your own (plans?). Who offers the biggest filter with the kits also.