  We develop a theory for frictional drag between two 2D hole layers in a
dilute bilayer GaAs hole system, including effects of hole-hole and hole-phonon
interactions. Our calculations suggest significant enhancement of hole drag
transresistivity over the corresponding electron drag results. This enhancement
originates from the exchange induced renormalization of the single layer
compressibility and the strong dependence of single layer conductivity on
density. We also address the effect of hole-phonon interaction on the drag
temperature dependence. Our calculated results are in reasonable quantitative
agreement with recent experimental observations.
