Some came with minimal output head P8R which had 33mm intake valves (Typically discovered on VTEC B-series) vs 31mm consumption (non VTEC B series), and The top had an 84mm shrouding vs 81mm for all other B series heads. When you’re wanting to extract even more power from a B16, https://b16honda25790.blogpixi.com/40131976/jdm-honda-replacement-engine-things-to-know-before-you-buy