A method and apparatus is used to provide DC stabilization and noise reduction in a multistage power amplifier. The power system may have a first generator set with a first engine drivingly coupled to a first generator, and a second generator set with a second engine drivingly coupled to a second generator. A catalyst regeneration event includes at least one of exposing the catalyst to a sufficiently high temperature over a time period that removes contaminants from the catalyst and manipulation of the exhaust gas composition to initiate andor accelerate removal of contaminants from the catalyst. The adjusted signature points form a digital signature which is stored for future identification of subject images derived from the image. The system includes one or more impact absorbing pads and means for reversibly attaching the pads to sports apparel.