It is generally recommended to replace the exhaust gaskets when swapping the exhaust system on a Harley-Davidson Twin-Cam engine. Here are a few reasons why:
Proper Seal: Exhaust gaskets are designed to create a tight seal between the exhaust ports on the engine and the new exhaust system. Over time, gaskets can become compressed, worn, or damaged, leading to leaks. Installing new gaskets ensures a proper seal and helps prevent exhaust leaks, which can negatively impact performance and potentially cause other issues.
Compatibility: Different exhaust systems may have variations in their flange design or dimensions. Using the correct gasket specific to the exhaust system being installed ensures a proper fit and alignment between the exhaust ports and the exhaust pipes. This helps maintain the correct flow of exhaust gases and prevents potential misalignment or exhaust leaks.
Cost-Effective: While it may seem like an additional expense, replacing the gaskets when swapping the exhaust is a relatively inexpensive preventive measure. Doing so can help avoid potential issues and the need for rework later on. It's a small investment compared to the potential costs of addressing leaks or other problems caused by reusing worn gaskets.
It's important to note that specific recommendations may vary depending on the motorcycle model, exhaust system, and manufacturer guidelines. Always consult the installation instructions provided by the exhaust manufacturer or seek advice from a knowledgeable Harley-Davidson technician or dealer for the most accurate guidance specific to your motorcycle.