See. Now we are getting down to it. They have always been black, so they are supposed to be black. And personal taste is, well, personal. And that's OK.
But for efficency they should be silver.
BTW, silver is THE color for exhaust manifolds, best color for an engine block, valve covers, is flat black - to help rid the engine of heat. Old Smokey Yunick trick.
Not for those doing restorations though.