33-2075 is the number that directly crosses to the OEM filter. If you buy from www.subaruparts.com this is the filter you will get. This is the filter I have in my WRX and it fits fine. I know there is another part number that you can use (33-2031-2) that will also fit the WRX airbox.
Not a lot. I think the turbo spools a little quicker and you can here it a little more but I didn't notice anything on my butt dyno! I think it will make a difference over a dirty stock (paper) filter though.
Guys guys guys....its not the (33-2031-2). It kinda fits but let me tell you the 33-2031-1 fits 10 times better. Trust me I have tried both. As for the 2075, I have no experience with that. Even though the Subaru OEM filter part number corss-reference to the 2031-2 the 2031-1 fits better..
Well, I ordered the 2075 one from Autozone and it should be in tomorrow, so we'll see how it fits. It was $41.99. I found the 2031-2 in the store and I compared it with the stock element and there were enough dimensional differences to warrant me waiting for the 2075 to come it. Thanks all for the info. Blazen- props to an awesome site by the way!
No prob. As far as results, seems like it gave the Rex a little more torque in the lower revs. Noticed as I'm cruising to work in 5th (stretch of highway driving) that I barely step on the gas to accelerate (up hill!) (not that I really had a problem beforehand), but it does seem to be a little stronger.