Being a long term user of Mytraffic6 I was looking for a updated version. Don't seem that Mytraffic has any updates coming near future I saw that Flight1 had released a beta release of their Ultimate Traffic. I used that with FSX long time ago and now they are coming with Ultimate Traffic Live, for P3D 4.
You can download a beta version here, and buy trough the installer. Very straight forward install. It's finds your P3D 4 folder and install the necessary files.
Before you start P3D you need to go trough the different config pages. Once done with these UTL loads automatically after P3D starts.
A nice feature with hotkeys use can use from the sim to increase or decrease the level of traffic