OK, this is a very esoteric and probably worthless question (and therefore thread), but why did the 1HZ valve cover change colour from silver to black at some point after 2009 (I think in 2010)? My two 1HZ's - 2000 and 2008 - are both silver, but looking at those that are for sale new today, they are black. Is there any difference or reason for painting the cover black?