Please see the posting ‘Consumption Tuning for various throttles‘ for more Innovative info on this topic. The fifth era or Black Top could be determined by the black plastic valve cover. These kinds of engines were being created from 1995 to 2002 and therefore are observed only on Japanese products. https://elliotdxnzm.thekatyblog.com/30406303/helping-the-others-realize-the-advantages-of-blacktop-4age