A peripheral intake port gives the highest mean effective pressure; however, side intake porting produces a more steady idle, because it helps to prevent blow-back of burned gases into the intake ducts which cause "misfirings", caused by alternating cycles where the mixture ignites and fails to ignite. Peripheral porting (PP) gives the best mean effective pressure throughout the rpm range, but PP was linked also to worse idle stability and part-load performance. Early work by Toyota led to the addition of a fresh air supply to the exhaust port, and proved also that a Reed-valve in the intake port or ducts improved the low rpm and partial load performance of Wankel engines, by preventing blow-back of exhaust gas into the intake port and ducts, and reducing the misfire-inducing high EGR, at the cost of a small loss of power at top rpm. David W. Garside, the developer of the Norton rotary engine, who proposed that earlier opening of the intake port before top dead center (TDC), and longer intake ducts, improved low rpm torque and elasticity of Wankel engines. That is also described in Kenichi Yamamoto's books. Elasticity is also improved with a greater rotor eccentricity, analogous to a longer stroke in a reciprocating engine. Wankel engines operate better with a low-pressure exhaust system. Higher exhaust back pressure reduces mean effective pressure, more severely in peripheral intake port engines. The Mazda RX-8 Renesis engine improved performance by doubling the exhaust port area compared with earlier designs, and there has been specific study of the effect of intake and exhaust piping configuration on the performance of Wankel engines.