I decided to make this post to keep DCT owners informed on what I have learned about running high boost on a DCT car. I currently own a 335is with Stage 2 +20T turbos, port injection, inlets, and supporting mods.

Here is what I have found out so far: MHD currently has issues once you raise the boost ceiling on an INAOS map. This puts a cap on your boost level at 21 PSI. Below are data logs of my car with the stock boost ceiling increased. You can see my trans struggles to shift due to the issue with MHD. It even causes the car to lose boost on some shifts. This is not a mechanical slip and is directly being caused by MHD.
http://datazap.me/u/artsoasis/bqe70-...og=0&data=4-23
http://datazap.me/u/artsoasis/bqe70-...og=0&data=4-21
http://datazap.me/u/artsoasis/inaos-...og=0&data=4-24

Martial is working on a fix, but no word on a release date. My trans has yet to slip at 535 whp level when I was using cobb. I'll keep pushing until I notice any slipping and dyno to get an estimate of what power level causes the stock trans to slip. I will wait a few more weeks, but I will go the JB4 route around mid February. Hopefully Terry can square me away.


The only car I have seen running high boost with DCT is a euro 335i that has upgraded clutches, turbos and uses JB4+BEF. His car uses a custom tuned Trebila BEF and JB4. I think he is able to get away without any issues because it's using the stock boost ceiling and having JB4 control boost.

Please post your experiences using DCT and high boost. I get the feeling the high HP cars with DCT will soon hold all of the 1/4 records.