Feilding used their overlap to quickly score for 15-7, and then regained consecutive kickoffs to camp in Collegiate's territory, scoring twice more to win 27-7.
That put Collegiate into the playoff for third with Manukura, who lost to PNBHS in the other semifinal.
It was nervous start for both teams as Manukura fumbled their kickoff regather attempt but won the tighthead to the scrum, only to lose the ball again.
Collegiate moved the ball around and despite a mis-timed pass that had to be regathered, they found the gap to go under the posts for 7-0.
Manukura struck back after getting a penalty for a high tackle, their runner bumping out of two tackles to score out wide for 7-5.
It appeared Collegiate might score just before the break with some more basketball-style passes getting them into position, but Manukura counterattacked with a brilliant try after ripping back possession and putting in a chip kick, which was regained and turned into a centring kick for the chaser to run under the posts to lead 12-7.
Collegiate came out more urgent after the break, regaining the kickoff and putting the ball through the hands until the gap opened up to run to the posts for another converted try at 14-12.
Manukura then added another outstanding try from inside their own half, going down the touchline and holding off the cover defence to again switch the lead 17-14.
Collegiate looked to start something in their own half, losing possession, but twice the forwards were able to force a turnover at the breakdown to keep hope alive.
Again, they let the ball do the work with quick passes and offloads, and the gap finally opened up to sprint right down to the far corner, using up a lot of time and regaining the lead 19-17 after the missed conversion.
Manukura tried to break free down the left hand side of the field from the kickout but were pushed out, with Collegiate taking a quick lineout and looking to hold onto possession to run out the clock.
However, the ball was lost coming into contact and Manukura had a chance off the last play, but Collegiate's defensive line held and eventually got a penalty for playing on the ground, which was kicked out for fulltime.
In the Open Boys final, PNBHS beat Feilding 22-21, which like the playoff for third was a reversal on the Saturday result, when Feilding won 26-12.