They've scored more points (682 points at almost 49 a match) and conceded fewer (132 points at 9.5 a game) than anyone else in the competition - and it hasn't been close.
Southern, who were second in both categories, scored more than 200 fewer points and conceded 93 more than their rivals.
However, both teams will be on an even footing for the final.
Kaihu come into the contest after a convincing 40-6 win over Pipiwai, while Southern subdued Whangaruru in a 24-12 victory.
Meanwhile, Kamo and Old Boys Marist will be tussling for top honours in the Premier Reserve final.
The two sides had slightly different roads to the final; OBM finished second in the round robin, while Kamo nabbed the last spot in the top four after a battle with fifth-placed Western Sharks.
Kamo then upset the table-topping Mid Northern 17-14 in the semifinals, while OBM beat Waipu 38-36 courtesy of a last-minute try and sideline conversion.
Kamo have been the slightly better attacking team (545 points to OBM's 525), while OBM have the wood on them defensively (241 points to Kamo's 335).
The teams split their first two contests this year.
The match kicks off at 11am. Entry for all games is $5.
Last five games: Kaihu v Southern
* Kaihu 19 Southern 0
* Southern 38 Kaihu 32
* Southern 24 Kaihu 18
* Southern 22 Kaihu 15
* Southern 24 Kaihu 14
Last five games: Kamo v OBM
* Kamo 9 OBM 0
* OBM 28 Kamo 11
* Kamo 31 OBM 12
* Kamo 44 OBM 3
* OBM 44 Kamo 14
