The largest port type available, this is almost exclusively recommended for racing. Some people can successfully drive these on the street, but it wont be a pleasant drive at low speeds.  With a full peripheral port engine, the side ports are filled in with epoxy and no longer used. These produce the most torque of any port type.  This is a brand new OEM mazda housing with the peripheral port machined and pressed in. Uses a wiggins style o-ring flange for a boltless connection. Same exact design that is in our worlds highest horsepower 4-rotor (naturally aspirated).  A 13b 2-rotor can produce up to 380hp with these housings and proper tuning of all external parts.  To top it off- The coolant jacket is machined and a dual o-ring plug pressed in to ensure a leak proof seal.