I am having the same issue, have since I bought the car with the IR injection (custom built) from the previous owner. He CNC'd a rather unattractive filter box out of high temp teflon butcher block type material with a corvetter panel filter on it. While this may breathe very well and filter very well, its ugly. I have been looking for a single filter for each stack myself, but just can't find anything as the top of each stack is almost 4 inches wide. Even the filter screens shown above won't fit, nor will the Roush based K&N filters. I think I have decided to buy a couple different filters from K&N that might fit and try them out. There are a few with long flange necks on them that would stick down into the stack and would be very easy to remove. Let me know if anyone finds anything they feel will work for my setup as well. Thanks.
James