We mean the stock intake and airbox from an SVT focus with a panel filter drop in. It looks like a regular focus intake but the snorkel is bigger. Only someone who really knows a focus well would be able to identify it. It was designed by cosworth. It's essentially a ram air intake and has Dyno proven better gains than a cai on the zetec.
You can usually find one used for $50. But you're talking maybe a hp or two difference between the two so not sure if it's worth it.
I'm confused. You say you can only have stock parts but you already have some bolt-ons....