Increasing volume steps for lower notification & ringing volumes.

As the title says, does anyone know of a way to add volume steps to the OP3? I am using OOS and have added 35 steps to the media volume using GravityBox but I can't find any Xposed modules or zips that increase the steps for notifications & call volume, I find both to be really loud and I don't want to use the slider to keep the phone on permanent silence.

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