When the pipe is removed start by adding the header pipe first. The trick is to put the whole exhaust on with all of the bolts left loose. This will help you manipulate the pipe and line it up easily. Some exhausts can be a little tight and will need to be twisted and pushed into place before tightening all of the bolts off.
Work your way from the front to the back of the exhaust until it is on and all of the bolts are done up with your hands. Double check the entire exhaust is lined up straight and in the correct place and from there you can begin tightening up all of the bolts.
Start from the rear of the bike this time and work your way forward. Once all of the bolts are tightened you can go through and replace all of the tensioning springs also. Replace the plastics on the bike and you are ready to roll!
Fuel injected bikes will adjust their mapping automatically once you have added a performance pipe so suit. But there will be more instructions for this included when you purchase any particular pipe as some brands may vary in information.
For dirt bikes with a carburettor you may need to re-jett your bike to get the fuel/air mixtures right. Consult a mechanic or your owner’s manual if you are unsure as if your bike isn’t jetted correctly it can severely effect your bikes performance or actually cause engine damage.