When your ECU thinks you are driving around in your refrigerator, it will advance the timing, right? So this mod (according to what the ad says) will advance your timing beyond what VW's engineers thought to be safe for any given temperature above 44 deg F. Increasing advance can produce more power, but advancing ignition too far leads to detonation (AKA ping, knock, pre-ignition) which is really bad for your engine. It can flake metal off the top of your pistons and break the rings and shatter the spark plugs. All of these metal and ceramic chunks will melt onto the exhaust valves or, if you are lucky, go straight into the hot side of your turbo, which will be spinning at about 80,000+ rpm when it all hits.
Passats have a knock sensor that retards the timing when it detects detonation (that is, after detonation has already happened) which will keep you from blowing up your engine. This mod basically thwarts all the hard work VW engineers did creating a multidimentional engine mapping program that maximizes power while skirting the ragged edge of destruction by bouncing your ignition timing off of the knock sensor. This mod is so inelegant that I can hear an automotive engineer wailing in the distance: "Why? In the name of God, why?"
I bet the guy that makes these also sells a whipped-cream can nitrous-injector system and an Estes model rocket engine adapter for the rear bumper.
