...G43 and G49 codes may need to added to your postprocessor.
T1
G17
G21
G90
...insert G43 Hxx here (xx= tool offset number of your choice) or somewhere before the 1st Z axis move
G0Z20.320
G0X0.000Y0.000
S16000M3
G0X18.411Y86.089Z5.080
G1Z-1.191F635.0
G1X16.864Y85.009F1524.0
...G49 H00 to cancel Tool Length Comp before Tool change