Originally Posted by warot
Not a regular member here, but was reading through. The valve opens only in second gear onwards from around 3000 rpm, but I'm not 100 percent sure about the rpm. This is for acoustic purposes only (think of a trumpet) and torque isn't affected.
P.S. I had an internship at BMW SA in the acoustic section, that's how I know.
You are right on the money
Some of you may not know this but I also work for Patrick BMW. I have been to BMWNA for some classes and they stated that the valve does not affect hp/tq