Like Hector said, the JRSC for the Focus does have a bypass valve in beteween the intake and the supercharger's output.
If you are designing one yourself, see if you can do something like the Powerworks Focus kit and integrate a intercooler into the intake manifold. Like this...
The JRSC is mounted upside down so that it blows up into a liquid to air intercooler. Very nice design. You can also see the bypass valve in that picture.
Heat is a big problem with the M45. It is soo small that when you start increasing the boost it REALLY heats up the air.
BTW, Hector that pics rocks.
HTH,
BP