The B grade side got off to a great start with Dylan Lewis scoring a try in the second minute of the game to set up a thumping 87-0 win, securing their spot in second place.
The A grade game was closer, with both teams putting everything into their performances during the first half with some amazing talent on display.
At the half time break, Mandurah had a small lead, looking to improve on a few mistakes, and put on some youth.
The plan worked as Mandurah started to break through the Irish defence, scoring a few unanswered tries, allowing Andew Taitoko to show off his skills with the boot, pushing ahead to get a bonus point win, finishing the game with a well deserved 43-5 win.
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Next Saturday Mandurah will be playing away, with the B grade travelling to Australind to take on Bunbury, kicking off at 2.10pm.
A grade will travel to Stratton to take on Swan Suburbs, kicking off at 3.30pm.