The thing to remember here is primary tube size. You want primary tubes that are the same or larger than your exhaust ports. Too large and you lose torque. Too small and you lose horsepower.

Let’s say that each of these Plattfuss Rubber Bands, made from old bike inner-tubes, is 2mm wide. You get around 70 in a pack, which requires 140mm (5.5-inches) of OG bike tube to make them. The ...