@Jimbo.Automates- would you consider a feature request for "send sys custom with params" to use the subject from the message defined under the AC configuration->emails/notifications->customizations for the "title=" parameter when sending the POST to pushover?
I think the subject is currently sent as part of the "message=". If the subject is left blank, then the "title=" could be skipped, resulting in the app name being displayed - this way there is user control to do this either way. I can confirm via network resources that when "title=XXXXX" is specified, then XXXXX is displayed in bold instead of the app name (which is redundant, not useful information).
Also, notify nodes are always displaying the app name as well - in that case, a means of specifying the title would be needed on the AC menu( with the other options) and perhaps if left blank then it results in the app name being displayed. Thanks for considering.