Most of what I do is WWII prop jobs, but FWIW keep in mind that exhaust nozzles are steel. The color of steel is slightly darker than silver. I've been using some acrylic paint from "Games Workshop" that brushes and sprays beautifully, much better than most of the silver or aluminum paint I've used. I think the color is "Boltgun Metal" or something like that, but for steel parts it works great. That particular color might be a little bit dark for exhaust nozzles though.
Also, the buckets frequently have some blackening inside from the carbon, and that can be reproduced with a little drybrushing. Some dark wash in the joints will add some depth to them as well.
Later ... Now that I think about it, the nozzles may be made of titanium or some sort of titanium alloy. If it is an alloy that would explain the differences in coloration.