For a power-increasing exhaust, try Predator in Welwyn Garden City, England, website www.predatormotorsport.co.uk. It´s not a 2-into-1 but gives much more power, especially when the inlet restriction is removed - around 80bhp (ps). The carburettors will probably need re-jetting. The system´s´s in stainless steel and guaranteed for the whole life of the motorcycle. Good luck!