I'm not sure how the turbocharged MP3's around here are setup, they may be setup in a way that a BOV is appropriate, but the MSP is setup to use a DV, so it would be best to stick with one of those. I'm brand new to the Mazda world, so I don't know how common engine computer upgrades are, but I wouldn't put BOV into a Mazdaspeed without a computer upgrade designed for one.