Kenny
Precoloured as in plastic molded in a silver colour or precoloured as in chrome-plated? If it's the latter, which I suspect, you may get away with not painting it, depending on the quality of the plating. I've done it a lot of times. Just be very carefull when you take it off the sprue and do some touchups where the plastic colour from underneath then shows through. The pursists will kill me for giving you this lazy way out, but if the plating's good enough.. well, I've done it plenty times. If not of a good quality, you'll have to remove the plating, (there's a couple of ways to do it, I tend to use the stuff you wash baths with, but test on a spare part of spru!) then repaint.
Obviously, if not plated, then paint. I'd suspect in silver/chrome. Show some progress in the MotoGP GB!