1. Select your prop and fuel.
2. Install your pipe and header. It's useful to have a friend hold the pipe with a rag.
3. Tach your engine at full bore.
4. Cut 1/4" off the back of your header.
5. Repeat steps 3 & 4 until you notice an RPM increase.
6. Continue the cut & tach routine but only make 1/8" cuts. Stop when no further RPM increase is realized.
7. Add 1/4-1/2" back to your pipe length and mount your pipe.