Something to note on the 8.1S exhaust system than generally doesn' get mentioned. The bottom of the manifold has a drain. This allows the entire system including the heat excangers (water, oil and trany) to drain dry. Hence, why there is no zincs on the 8.1s. Which also helps with extended life. Ever look at the side exhaust on first start and it takes several seconds for water to spit out. Well that's why.... the system is refilling.