If you want to do maintenance tasks for your Vespa LXV 150 then it is usually recommended to have a Workshop Manual to keep just for reference just in case you want to know ways to strip off a particular component including Exhaust and install it again properly.
Vespa LXV 150 Workshop Manuals provide you with specific diagnostic guides for the car so if something is wrong it helps you ascertain what the situation is and tips to correct it. After that you can analyse if you can do this yourself or in the event the job is just too big you can book your LXV 150 in with a nearby garage.
Vespa LXV 150 manual