For high performance use, a wooden prop can be better. For trainers and sport planes, the durability of a nylon prop far outweighs the small performance loss.

An idle bar is a piece of metal that used to partially cover the coil on glow plugs. It was there to protect the coil from splashing fuel at lower rpms. This helped it stay hot while idling. Manufacturers have improved the coils enough such that idle bars are no longer needed. Plugs such as the OS #8 work well in most engines.