Dave,
Do I have a deal for you! Get yourself one of these top breather air filters from Edelbrock. They are rated at 1,000 cfm, and flow air in directly thru the top. Perfect for the scoop on a Cobra. But throw away the foam element that comes with it, and get the open cell foam that Sears sells as filters for its dehumidifiers! Just cut it to fit.
This is what I use. The air comes into the hood scoop and directly down into the filter. Plus you can use the Stubstack and not have to worry about top clearance like with a traditional air filter that has a lid. And if all this is not enough to get you excited, the cost of these filters is only $16.99 in Jegs.
http://www.jegs.com
Once you are at the site, just do a search on air cleaners. Its the Pro Flow one by Edelbrock. You can also get the Stubstack there. Just search on the name.
Ed