yes
plastic is actually a good material for some parts because it prevents the transfer of heat from the engine block to things that shouldn't get as as hot as the rest of the engine, like the air intakes.
modern fiber-reinforced plastic is durable and very resistant to damage, it won't corrode, it doesn't need paint, and it cleans off nice.

some people seem to be deathly afraid that the bits will warp or melt or something dumb but if your engine is getting up to 500, 600 degrees F on the regular you probably need to make sure you aren't in fact driving a nuclear reactor.