FYI, the 9psi pulley is a simple replacement and costs $60 from Vortech. Obviously, it requires retuning of the R4 software, but due to fact that boost is RPM dependent you can have one map that works for both 8psi and 9psi (since 9psi actuates different cells in the map along the RPM band).

I'm not sure if I'm making any sense.

--Steve