Abstract. We consider a class of C 4 partially hyperbolic systems on T 2 described by maps Fε(x, θ) = (f (x, θ), θ + εω(x, θ)) where f (·, θ) are expanding maps of the circle. For sufficiently small ε and ω generic in an open set, we precisely classify the SRB measures for Fε and their statistical properties, including exponential decay of correlation for Hölder observables with explicit and nearly optimal bounds on the decay rate.