5 THINGS YOU NEED TO KNOW
If you don’t get the design of these correct you’ll always struggle. Length is critical and a bigger bore isn’t always better – imagine trying to wash your car with a 3-inch-bore hosepipe – it’s all about pressure. Some bikes have balance pipes in between the primaries, to reduce pressure spots.
These are ever more important with trackdays having quieter noise limits in a bid to keep nearby residents happy. It’s all to do with how much sound-absorbing material you can get around the internal perforated pipe, so we use a slightly narrower pipe giving more space for no noticeable power loss.
Stainless is not expensive, easy to work with but can snap. Titanium is light, but expensive, timeconsuming to make and hard to repair. A good compromise is stainless headers with a titanium silencer. Carbon can’t be repaired.
You should replace the sound-absorption material every year on the exhaust of a 1000cc bike, every two years on a 600cc machine’s system. Use a good alloy wheel cleaner to bring your stainless system back to new, but be careful not to spill it on any carbon fibre.
5 Perfect examples
OE manufacturers are governed by many restrictions surrounding emissions, space and noise when they produce their systems, but in my opinion the pre-2015 BMW S1000RR system was near on perfect, the 2016 ZX-10R is good, and the current model R1’s has lots of room around it to keep it cool.
OE exhausts are governed by legislation restrictions
Bigger isn’t always better with primaries
Removable baffles are now a common sight at trackdays