Flashing systems for use with metal and non-metal roof systems are provided having a generally planar lead base defining an aperture, a generally cylindrical structure attached to the base in surrounding relation with the aperture and projecting upward therefrom, and an adhesive sealing membrane attached to the bottom of the base for connecting the flashing to a roof. A flexible plastic downspout allows flashing system to adapt to various roof slope and roof penetration configurations. The downspout may be include a plurality of diametrically reducing stepped sections such that the installing technician is able to simply cut the stepped plastic downspout to the size that will accommodate the roof penetration pipe.