Removing paint - Changing Colour?

Anybody know what's the best way to Re-spray a bumper?
I recently bought a Wings West rear lower wrap from a mate. It has already been sprayed Silver but was never fitted. I want to spray this Red. Do I need do remove the silver paint or can I paint over it?

Any suggestions?

You can probably just primer over the silver and then paint it the color you want.

NO NO NO NO NO!!
First you have to clean the bumper, then sand it or matt it so that the previous color isn't glossy, then you paint 1 coat or primer on it.
the you have to sand it with high grid sang paper (500+), then prime it again, then paint on the new coat of your colour

Thanks for your help - I didn't think I could just paint over it, it would probably peel off after a few months!

although i have been told by many people that painting over a prepainted area is the best way for the new paint to stick, so i dont know, it seems as though it should be removed.

try to hand sand the paint job to the primer... if u can tell what color primer it is.. then paint again