The only reason I installed my rain/light sensor was because I needed a new windshield. I got the sensor, mirror, and wiring harness all from ebay in a package. It cost me about $170 and about only 2-3 hours of work if you've done wiring to the CECM before. It's not hard at all of you have a good idea of what you are doing and plan to get a new windshield. The replacement windshield I received was even Saint-Gobain Sekurit, which is basically the OEM glass without the VW logo. What I enjoy most is having the rain sensing wipers and the leaving home feature. My LED DRLS and fogs come on when I press the unlock when it's darker outside. I literally don't touch anything anymore once I get in my car. The rain closure is also a cool feature to show off.