Description Reviews The Detroit Tuned Bypass Valve is a re-worked new OEM valve that is modified by Detroit Tuned to eliminate the "Yo-Yo" in the MINI Cooper S's, the yo-yo was more prevalent for the early 2002-2004 cars but could happen in any of the years. What is the "Yo-Yo" effect? It's the opening and closing of the valve around 2500 rpm's so that it feels like you're stepping on and off the gas, but you're not. So we added a stronger spring to overcome the vacuum condition that it sees so that it will not open as soon or as much. Our BPV closes at 6" of vacuum, as opposed to the factory value of 0" of vacuum. MINI tried to fix the problem in the 2005-2006 cars with a ECU tweak but it never really worked correctly for a lot of cars. This was the main reason our BPV was created, but there are a lot of benefits, read on! The DT BPV uses a stiffer return spring, resulting in quicker boost generation, and thus quicker throttle response and transitions. Most cars see about 1psi total more boost @ redline. The butterfly assembly is also adjusted as much as possible to close fully, allowing for maximum boost. This is done by centering of the butterfly door and adjustment of the set screw that sets the openness of the butterfly. Perfect for the aggressive driver or racer. It is possible to see a very minor loss in fuel economy, but you will see a great improvement in throttle resolution and smoothness. Full how-to instructions (below) and all necessary hardware is included. Easy to install in about an hour. No core charge so there is no need to return your old valve. This part only fits the Gen 1 2002-2006/7 Cooper S with the W11 Tritech motor. Instructions Download Article 5 Reviews