Penrith-born Courtney will arrive in Sydney sitting ninth in the 2021 drivers’ standings.
"It looks tough, doesn't it?” the 2010 series champion said of the new scheme.
"We've made a pretty simple change to the Boost Mobile Mustang but it looks like a whole new beast, and it's going to look amazing under the lights in Sydney next weekend.
"We're all really excited to get back on track, I know we're all focused on making sure that car 44 is at the front, and if this car races as well as it looks, we'll be up there for sure."
Tim Slade and Scott Pye will also carry updated schemes for the Sydney events.
Courtney will return behind the wheel of his newly-coloured Mustang at Winton Motor Raceway on Tuesday.
All sessions will be broadcast live on Fox Sports and streamed via Kayo. The Seven Network will broadcast live from 3:30pm AEDT on Saturday and 12:30pm AEDT on Sunday.