Installing a manual boost controller in Mazdaspeed is a bit more complicated than the average turbocharged car but not substantially. What’s important to know is that the vacuum/boost nipple on the turbocharger’s compressor housing has a restrictor installed from the factory; this was done by Mazda in accordance with their boost control scheme. As such, this can’t be used as boost source for a manual boost controller.

Now, this is the point where I mention that having a boost gauge shouldn’t be an option. I love my gadgets but I wouldn’t trust an ODB2-based logging tool to make sure I’m not about to put my pistons into my oil pan.

I’ll leave most of the talking to the included diagram below, but the gist is that you’re going to end up capping just about everything involved with stock boost control.

Couple of installed images: