A new silencer is perhaps the most common serious change most new motorcycle owners make to a motorcycle. Throw a new exhaust pipe on it.
On the face of it, you get a bit more power, lose a stack of weight, and get a nicer sound. And on some motorcycles – Suzuki's B-King, BMW's K1300S, etc... – you can replace questionable stock aesthetics with a sleek aftermarket exhaust replacement.
But in the past few years, the increasing integration of exhaust design into the motorcycle has made it much harder for aftermarket exhaust system manufacturers to make suitable replacements. Also, the exhaust manufacturers have got wiser to exhaust header pipe design – if there's any extra power or grunt to be gained from making smarter pipework, chances are the Honda, Kawasaki or Yamaha have had a go at it already. What this means is that the power gains of a full exhaust system are often not massively more than that gained from a simple end-can change. Finally – many full race exhaust systems are designed in conjunction with race bodywork and engine race kits, so you may need to change things like the sump and bellypan to make it physically fit. And it may only give the best performance with with racekit camshafts, ECU, etc...
So while those in need of maximum power, and ultimate weight loss for the race track will pay the 40,000 or more needed for a complete exhaust replacement system, road riders who only want a better sound and a few extra horsepower for trackdays can just fit a new exhaust end-can. Exhaust system importers and manufacturers we spoke to confirmed that sales of end-cans are increasing at the cost of full exhaust systems.