After I met a deer twice. and buying the car from the insurance company after the 2nd deer (in a year). While my car was being repaired. I started reading online reviews of deer whistles. Most of them were 50/50 successful. Installation was pretty easy. Instead of going through the firewall. We decided to just run the cables up to the hood hinge. then through the driver's front door (near the hinges). Installed in a small hole on the left of the steering wheel. I bought a corrugated pipe for wiring. so that it is not (subsequently) clamped by loops. VOILA! I managed to live off my car for another 3 1/2 years before finally trading it in for a new car. Not only have I stopped hitting a deer...in fact, I've never hit ANY animals. Very rarely SEE animals on the road (when the alarm is on). The only animals I ACTUALLY saw were either standing still trying to figure out where the sound was coming from...or turning to face the direction they were coming from. When I bought a new car. I ordered a new alarm first and it was the FIRST ONE installed (at the dealer this time)! Best buy ever!