Tuning advice for Quad X with 18" props

Hey friends! I’m looking for any tuning advice. I’m familiar with tuning, but it’s mostly been on smaller rigs so far. I’m looking for maximum efficiency and smoothness.

Build
somewhat stretched (on the pitch axis) 1000mm frame
Pixhawk Cube
Here+ RTK
Hobbywing Xrotor 50amp ESC
KDE 4215 460kv motors
Mrobotics PDB
Tattu 22000 6s battery

http://arduplotter.com/view/5b08635f8905692d188d8019