The West Aussie got the job done at the Perth Motorplex in front of a huge local crowd – that unfortunately were treated to just five Top Fuel machines making the trek West.
Defending Australian Champion, Darren Morgan bowed out in the opening round of heats – losing to Harris.
Cowin made the final by first beating Mark Sheehan and then getting past Phil Lamattina.
In winning the final, Harris set the lowest ET of the weekend – a 4.72 second pass.
In the other key category, Top Bike, Chris Matheson defeated Mark Drew in the Final to take the win.
He was fortunate to take the win – overpowering the track – but being awarded the victory when Drew crossed the centre line.