An imaging system comprises a transmitter, a receiver, an antenna array ; and a controller for directing the transmitter, the receiver, and the antenna array to scan a volume containing an object. Another optical attenuator is provided with a dopant concentration in a technically realizable range which increases the difference in optical attenuation of two different kinds of input optical signals. The pulling means is an elongate woven pulling means having different warp densities which is fastened to the airbag by a first end portion of low warp density, preferably by stitching, and is coupled to the activation unit by a longitudinal portion of high warp density. The air cleaner housing bottom base plate includes an aperture that aligns with the rear portion of the inner air directing plenum and also aligns with the location of the rear cylinder of a twin cylinder motorcycle engine.