are they not just alloy - not chrome - if alloy go with auto solve and elbow grease, it can work on chrome also but is a little too abrasive so I wouldn't recommend it. If it is alloy and well past it you may need to take them off and get the polishing wheel to them (not the fins on the intercooler) get the metal to an even finish then use very fine wet and dry to give the dull factory alloy finish. the dump valve I would remove, strip down and polish