If you wish to perform maintenance tasks on your own Suzuki GS 450 L then it will always be a good idea to own a Workshop Manual for personal reference if you need to know proven methods to take off a specific component for instance the Brake Discs and install it again correctly.
Suzuki GS 450 L Workshop Manuals provides exact diagnostic guides with regards to your car therefore if something is playing up it helps you ascertain what the situation is and the best way to make it better. You can then analyse if this can be done on your own or that the job is just too big you can still book your GS 450 L into a decent mechanic.
Suzuki GS 450 L manual