APR DV100001 Motorsport R1 Diverter Valve for Audi

What the heck does a diverter valve do?
Your stock valve in your car regulates your turbo power. At idle, your valve is open from vacuum pressure. When you depress the throttle, the diverter valve begins to close. When fully closed, turbo boost is allowed to be delivered to your engine. When you lift the throttle, the boost pressure is released from the valve into your air cleaner box. Inadequate/defective valves have extended lag, loss of boost and sluggish throttle response. A new diverter valve can clear up the previously mentioned problems. Also, if you have a chip, you need an upgraded valve now. Chips simply overtax standard diverter valves.

What cars can use a diverter valve?
Any car turbocharged car from Audi, VW, Porsche, Saab, Volvo, and others. Specifically Audi A4 1.8T, A6 2.7T, TT, S4 Bi-Turbo. VW Passat 1.8T, Golf 1.8T, Jetta 1.8T, Beetle 1.8T. Porsche 993 and 996 turbos.

Is a diverter valve the same thing as a "blow-off" valve?
No, not technically. A blow-off valve sends the "boosted" air into the atmosphere rather than the airbox/air filter. This is why they usually make a loud noise from the air releasing. This offers no real performance gain and in most all cases will cause sophisticated engine management systems, like in the VW or Audi cars, to incur errors and drivability issues.