Hello,
At the moment, the only trusted process is the Windows Search Indexer and it isn’t customizable.
Virus and spyware scans include a feature that is called Insight that lets scans skip trusted files. You can choose the level of trust for the files that you want to skip, or you can disable the option. If you disable the option, you might increase scan time.
Check this Thread with similar issue:
https://www-secure.symantec.com/connect/forums/files-trusted
Secondly, check these Articles:
About the files and folders that Symantec Endpoint Protection excludes from virus and spyware scans
http://www.symantec.com/docs/HOWTO80947
Security Response recommendations for Symantec Endpoint Protection 12.1 settings
http://www.symantec.com/docs/TECH173752
Hope that helps!!