Maybe in theory but I haven't experienced any loss in rpms, so therefore no loss in power. The on-board glow is simply because 1) the OS twins have been known to drop a cylinder from time to time and its extremely beneficial to be able to reignite the cold cylinder and keep the plane in the air, and 2) makes starting the engine infinitely simpler not having to attach any glow leads (let alone 2 leads) to start the plane.