Forget about those pipes. The stock exhaust was very good on the 97-99 twins. Install the .6 head gasket and larger rear heat exchanger as the performance of those things suffers if they get heat soaked. Leave the mains stock and run 91-93 premium.
If you really wanted to add some power the best bang for the buck would be some trail porting by an experienced porter.
If you really wanted to add some power the best bang for the buck would be some trail porting by an experienced porter.