There are many points to be considered depending on each configuration and used features. please check Upgrade and Revert/Downgrade Guide.
http://mysupport.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=526036This case is upgrade between same major release, so it is easier than that across major releases.
Upgrade advisor in MyAutoSupport may also helps. It gives you detailed upgrade steps.
By the way, if you have no reason to use 8.1.4P4, better to use latest patch release.