MacBook Pro Retina 2013 memory frequency limit
I am 99% sure that the 2013 MBP will not be compatible with faster RAM than 1600MHz, Apple spec sheets state this, with a memory type of DDR3L.

DDR3 is capable of being faster than 1600MHz; DDR4 has different latencies and clockspeeds to DDR3.

I think you're on a hiding to nothing trying to de-solder DDR3 RAM and solder in DDR4. You can try if you like, but I suspect you will just end up with an expensive (but shiny) tray.