You should buy this SP4. Motorcycle exhaust pipes are fitted with silencers at the end to reduce the noise from the engine. The silencer attached at the end of the exhaust pipes causes the gases to expand so that any noise is expelled.
Lextek Stainless Steel SP4 Polished 300mm Exhaust System Silencer Chrome Rear
Lextek Stainless Steel SP4 Polished 300mm Exhaust with Link Pipe Silencer Rear
Lextek Stainless Steel SP4 Polished 300mm Exhaust with Link Pipe Silencer Chrome