Racing Beat offers a complete RX-7 high-performance exhaust system for the 1984-85 13B (GSL-SE) RX-7. This system includes our Road Race Header, a Power-Pulse Presilencer, and our legendary Power Pulse main muffler. The Power Pulse Presilencer unit is equipped with an exhaust backpressure pickup tube that allows the correct operation of the 6-Port intake actuators. Be careful, if you are considering a replacement exhaust system that does not have this important feature, your intake system will not perform correctly and a noticeable decrease in high RPM performance will occur. These components attach to all stock mounting points, and include all necessary gaskets and hangers. The only component not included is the factory connecting pipe that mounts just ahead of the main muffler. There is no horsepower to be gained by replacing this pipe with a larger diameter assembly. If your factory connecting pipe needs replacing, we suggest you contact your local Mazda dealer or muffler shop. These exhaust systems offer excellent horsepower gains when you require a muffled exhaust system for your stock-ported engine. The actual horsepower increase depends on which year/model stock RX-7 exhaust system you are comparing to, but a 22% increase at 7000 rpm is typical. Thanks to the combined efforts of the Power-Pulse Presilencer and the Power Pulse Main muffler, the exhaust noise is only slightly higher than stock, with a very low, pleasant character.