1) Pull up the carpet on the passenger side (pop up two plastic, grey, round holders) and Ive found it easier to pop out the plastic guard on the bottom of the door rail (where the carpet meets the bottom of the door frame)
2) you will see a large metal plate (~1.5 sq ft) with 3 bolts and 1 nut (located higher up towards the front), take those out
3) the wire you will want to tap is clearly illustrated here http://www.avic411.com/forum/viewtopic. ... hlight=wrx and is what i used to tap my 07 LTD WRX. It was weird at first it was reading 2x my actual speed then "learned" the correct c