If you need to carry out adjustments on your own Suzuki Boulevard S40 then it is usually recommended to own a Workshop Manual for personal reference should you need to know methods to strip off a specific component such as the Exhaust and match it again in the correct manner.
Suzuki Boulevard S40 Workshop Manuals provides precise diagnostic info on your car so if something is broken it helps you work out what the problem is and some ways to fix it. After that you can analyse if you can do this by yourself or in case the job is just too big you are able to book your Boulevard S40 into a decent mechanic.
Suzuki Boulevard S40 manual