Gary,
   I believe that you need to put the parking brake valve downstream of the
master cylinders, not ahead of them.  That will require a split valve, like
the one Lancair sells.  I put mine between the outputs of the pedals and the
bulkhead fittings that brake lines pass through out of the fuselage.
Downstream of the valve is all aluminum tubing and high pressure hoses.  By
putting the valve there, you relieve the upstream pressure from the master
cylinders and the associated plumbing between them when the brakes are set.
   I only use my parking brake long enough to put in chocks in the event I
park on a sloped surface, then I release it.  So far, it works as advertised
and was very easy to install.
   Also, I plumbed my brakes as called for in the book.  They work fine and
there is no difference in feel between the left or right pedal (unless there
is some air in one of the lines).
   Skip Slater
   N540ES