Bear with me on this as I know it's lengthy.....

Does your tuned R56 overboost? If so I just might have a solution for you.
Having previously owned and worked on a highly boosted ( >22PSIg) Golf TDI, overboost was sometimes an issue. The TDI would actually overboost to 30PSIg. The TDI community uses a simple manual boost control valve to stop the problem. If you're interested in purchasing a boost control valve after reading this post just click the provided link. I've purchased and used two of these to date. You can buy your boost control valve by clicking here



After swapping out my very tired turbo with 85K miles on it (about 50K miles were ECU tuned) I suddenly had a new problem with the MINI. It was dumping boost with the aftermarket tune files. I don't believe that it's a tune related issue but probably has to do with all of the modifications to the MINI. My tune files are set to stay below the overboost trip points that would cause the ECU to dump all boost. I also think that my turbo was already not right when my MINI was first tuned.

After analyzing a ton of data from the Android Torque APP (sorry, iPhone people, you don't have this APP) it looks like the MINI is not overboosting but the boost is simply spiking. This boost spike is all the ECU needs to see to dump boost down to about 7-8 PSIg. Maybe having a much better flowing intake and a high flow exhaust system is simply allowing the turbo to spool up more quickly which is inducing the spike.

I Installed a boost control valve on my MINI ten days ago and there have been no boost dumps since installing the boost control valve. What I do experience now is full boost (20 PSIg) until I lift the throttle.

The boost control valve is a simple ball check valve with a spring to keep tension on the ball. You set the relief point manually for the boost control valve. It comes with two springs; you'll need to use the high pressure spring.

When boost spikes or the MINI overboosts the spring compresses and the excess pressure is routed to the turbo's internal wastegate. This action allows the wastegate to slightly open and divert some of the exhaust gas away from the exhaust turbine side of the turbo. When the boost spike or overboost condition is gone the boost control valve closes, which closes the wastegate, and your still in full boost. Boost spikes are very bad for both your engine and the turbo so installing the boost control valve is a win-win situation for your MINI.
Installation is straight forward and fairly simple. If you've installed a boost tap port you can tap off right there for your boost feed to the boost control valve.

Since I'm using the Android Torque APP I've removed my boost port tap so I simply tapped into the noise maker plug on the turbo cold side piping by drilling and tapping the plug to install a 1/8" NPT nipple. If you haven't removed your noise maker, you should. Here are a few pictures:




For tapping into the line which connects to the turbo's internal wastegate see below diagram:



Where you place your boost control valve is simpley a matter of choice. I used about 5 feet of 3/16" fuel line and a "T" connector to connect everything into the system.

The screen capture below is from the Android Torque App which shows 20.5 PSIg of boost. Solid boost with no boost dumps.