Here's a little info on my empeg install... Jim Hogan was a big help on cutting the bezel.

If you had an option to add 30hp to your WRX and get better fuel economy, a "valet" mode to make your car safe for valet parking, an anti-theft kill switch and OBDII code reader for $555, would you get it? Oh yeah, it requires no tools or hardware changes to your car. If so, check this. Mine's on order. It is simply the coolest thing ever for a stock WRX. And if you do change things like exhaust or turbo, you simply tell this handheld device what you've done and "bam" your car is tuned for it. (It's not the same as a custom dyno tune, but that will be an option in a month and you only pay the differance). 100% safe.