I belive Downey is it. From time to time, I've seen someone selling it on Ebay, but don't recall the brand name.

If you want to do it cheap, you could just buy the standard 4" cone filter, and use a zip tied to hold it after the air sensor. I've bought a basic cone filter for my Integra GSR last year. Before putting it on the Integra, I decided to play with it to see if it would fit the T. It does well, just doesn't look all that great. But the filter was only like $20 from Walmart. Anyway, I took it off and put it back on my Integra. I may get another one in the future.