  We present detailed experiments on transient growth of turbulent spots
induced by external forcing in plane Couette-Poiseuille flow, which are studied
in the framework of linear of transient growth. The experimental investigation
is supplemented with full theoretical analysis. We compare quantitatively the
experimental and theoretical results, including maximal gain and the time at
which it occurs. We also present the limits of validity for the application of
the linear theory at high amplitude perturbation and Reynolds number, showing
experiments with self-sustained states.
