First question: do you want an exhaust pipe for competition – or track races – or for your street bike? The special exhausts – mostly sports – that you can find in stores basically meet these two requirements, so make sure you don’t use a racing one on your street bike.
Or, at the very least, don’t remove the “dB killer“, an often discreet performance plug that can “standardise” an open exhaust so it can be used on the street without receiving a fine.
Why? Well, simply because it isn’t safe at all, on the contrary, your motorcycle draws unwanted attention in exchange for noise. And the noise doesn’t mean horsepower, but it’s a “defect” that decisively affects the reputation of the entire motorcycling community.
Just think that a motorcycle’s exhaust pipe is optimally configured to its internal thermodynamics (cylinder head design, valves, distribution, camshafts, etc.) and, above all, to its power, and this, nowadays, includes not only the intake, the injection, and the exhaust itself, but something even more important, the electronics that, through the ECU, are the real brains behind managing your engine.
Add to this that modern motorcycles have great possibilities for regulating the engine’s performance. Changing the engine “maps” (Sport, Racing, Urban or Rain, for example) that affect its throttle response – in many cases, using a ride by wire potentiometer, with no throttle cables – and at maximum power. Ultimately, all these parameters interact in such a way that any change to the exhaust may not be convenient and “deconfigure” a carefully well-chosen factory set-up.
Just think that a thousand Japanese engineers can’t be wrong. In order to define an exhaust pipe that complies with Directive 2005/30/CE, a thousand tests have been carried out not only on the dyno to get more or less horsepower at full throttle, but also to get the best response from the accelerator, avoiding faltering and surging, throughout the entire rev range!
The reality is, and you can go to great lengths check this, unless a careful adjustment is made to the electronics, a simple change to the exhaust pipe for a more open and noisy one – and more if the catalyst is removed – doesn’t usually offer better performance, but often actually makes engine response worse. Usually, the only benefits are a lighter, more racing look… And a whole lot more noise.