RR-3301 I believe is what fits the SVT Focus. To remove the bottom portion you need to buy a case vent filter as well... K&N makes these or you can get a cheap one from the parts store... Either one for directly into the case or into the vent hose and remotely mount.
I had it on mine and removed it as my car is 3 days from lemon status and is going in for service on Thusday... Hopefully making my 30 days mark!!! NEW 04 HERE I COME!
checkers would have it (i work for kragen, which is the same thing but in CA). they'd have to order the K&N, but they might have some cheapy cone filter that you could just stick on the end. as far as the breather (case vent) filter goes, that can be taken care of in a couple ways. easiest would be to buy a generic breather filter while your at the parts store. if you go to checker, look in the spectre section (black packaging). they should have one where you can stick a plastic hose adapter in the end and stick the breather hose on the other end. if you can wait til saturday evening, i can even get you the P/Ns of everything you would need. the other way is to leave the lower portion of the box and just let the cone filter rest in it, that way you can still hae the stock breather hooked up.
well, the breather isn't what's really hindering performance. what i think mofo eant was that this whole mod really doesn't gain you a whole lot more than a "buzz." it's louder, sure, but the old butt dyno says that there's not extra oomph. as fas as leaving the bottom of the box goes, i did it, but the filter rattled against the sides. maybe that's the buzz mofo was talking about.
nah i just meant it kind of sounds like an air intake, but it doesnt really gives you as much air flow, and in order for it tobe ramair youd need some sort of scoop feeding air to the filter, most likely from the hood, but yeh i have a real intake now and its lots better