The piping design of the NSX exhaust behind the catalytic converter was changed by the factory in 1995, and again in 2000.
1995-1996 factory exhausts use the same design as the early cars with the addition of adaptor pipes between the exhaust and converter. In 1997, these pipes were integrated to the exhaust design. In 2000, the design changed slightly again. To install an aftermarket exhaust, 1997+ NSX owners must use these adaptor pipes to correctly fit the exhaust. 1995-1996 owners may use their factory adaptors. However, since the factory pipe diameter is smaller than aftermarket exhaust and headers, we recommend customers with these cars to upgrade to these pipes for maximum unrestricted airflow.
Our exhaust sold for 1997 and later NSX include these kits as they are required for mounting of the exhaust.