Choosing an exhaust system

In Tech, Tech Talk Tuesday

WHETHER you want them for aesthetics or you’re trying to change the characteristics of your bike’s power delivery, aftermarket pipes may well be the answer.

There are plenty reasons why you might be after a new exhaust, including tuning, a new sound, passing noise tests, power and weight.

You might even need one to quiet down your bike – there have been reports of newer big bore Ducatis not passing standard noise tests with stock pipes.

Whatever system you’re after, make sure it comes with a baffle. For those pesky 98db days at the race track, a baffle may cut down your power, but it’ll get you on circuit without fuss from the venue operators.

Exhaust cans range from the shortest of the short (less than 150mm) to the longest of the long (over 450mm), and they all provide different tuning characteristics…

And after you do pass noise, don’t be the knob that uncorks your silencer half-way through the day because you’re trying to break lap records. Not going to happen.

Most exhaust companies, whether selling a full system or a slip-on muffler, show performance gains as either numeric totals in torque and horsepower or as dyno charts from actual testing.

If you’re fortunate enough to have access to dyno results when shopping around, pay attention to how the power delivery changes between a standard system and your choice system.

Usually the ‘stock vs X’ comparison will show peak gains or losses in horsepower, torque, weight and noise levels, but again it’s how the power and torque change that really matters.

Traditionally, for lack of a more in-depth explanation, shorter cans are better for top-of-the-range power and torque while longer cans generally provide more in the way of low and mid-range benefit. So the more power you have available, the more control you require.

Check out the big boys at BSB and even World Superbike. Between the early and middle parts of the season, you’ll sometimes see different end cans going on and coming off the bikes – it’s an important tuning tool for the engineers.

This is not as to say that you can choose the perfect system by picking a longer or shorter one, because there’s way more that goes into finding one best suited for specific applications – and that’s where bespoke exhaust manufacturers come in handy.

Core size, core perforation, back pressure, can material, heat loss (header material), tip style, packing, header length and header style (4-1, 4-2-1, 2-2, 2-1, 3-1, 3-3) all come into play. But we’ll leave that to the scientists and get on with the riding.

*Images: Paul Jinks

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