These graphs seem reasonably scientific, despite the lack of pure figures. I believe the comparison is to a S6 13B-REW engine. It's interesting because Mazda likes to tout that their exhaust ports in the Renesis are significantly larger than those found in the 13B-REW. This graph shows that to be true. What is apparent is that the peripheral exhaust ports are open for a longer period of time than the side port exhaust and that side port exhaust eliminates overlap. I did a crude calculation and and the total port area over time for the exhaust ports is approximately 50% greater for the peripheral exhaust compared to the Renesis' side exhaust.