Just be careful if it is new. I've got an eclipse also and the guys on the board had a lot of trouble with the early ones having faults. I think a big on was it rubbing on the battery screw which broke a hole in it and made the engine inhale metal shavings. Hopefully those problems don't exist on the WRX
If you haven't already done so, you need to remove the intake silencer from the fenderwell.
I've heard that the piping is a tight fit and needs to be forced into place... mounting is a cinch, but the filter must be attached with either the bumper off or the underpanels removed (if you've removed your intake silencer this way, it's the exact same method).
Access to and maintenance of the filter can be performed by simply removing the plastic underpanels.
The filter element itself, on a stock-height car, is at least 12" off the ground, so avoid small streams, if at all possible.
if you any of you are interested in the Injen CAI, Jermaine Johnson of Team Unison, a local Celica club ( http://www.teamunison.com ) can get you the piece of $200 shipped i'm pretty sure. If you're interested, contact him at [email protected] . some of you may have met him at the Shinestreet meet a couple weeks ago, he drove in with all the celica guys.