That's why I said Overboost.com. They have the Apexi filters with the flange for $69.95. Not that much more than a K&N. No oil/grease and lifetime filter, just wash and let dry.
I am waiting for mine right now to replace the AFE filter that came with my ION intake.
You want the 75mm one (the same as I am getting)
http://www.overboost.com/obs/product.asp?pid=34278&cat_id=4&cat_name=Intake%20/%20Induction&sc_id=78&sc_name=Intake%20Accessories
But you'll have a one time expense of getting a silicon hose to go with it if your current filter isn't being held on by a coupler. I don't know how the MHP goes into the wheel well, but I would imagine getting a 45 degree coupler would pretty much let you position it however you want. If it goes into the wheel well and bends (like the Injen) then you'll probably just want a straight 3" coupler.