Player/manager Paul Maguire said while they entered as a competitive squad, the step from Casual grade to Open at national Marist level was a daunting prospect.
On opening day Saturday, Whanganui Marist took on Palmerston North Marist Banshees, beating them 3-0, then dealt to Wellington Marist 1-0 before a 1-0 victory over Palmerston North Marist Grelts.
On Sunday they drew 1-1 with Birkenhead Barons & Hibernian to make the Symbiosis Cup final against Palmerston North Marist.
"We went 2-0 down in the first half to a very good Central Federation side, Palmerston North Marist," Maguire said.
"In the second half, we came out fighting.
"Midfielder Taco Rangi had a bullet shot incredibly saved, and then Scott Burney finished a flowing movement to draw it back to 2-1.
"PN Marist then had a player sent off and from then on we peppered the Palmy goal repeatedly, only to be caught on the counter attack and concede with the last kick of the game."
Maguire said while the team could take pride in their runners-up medals, there was a feeling that they let one get away after starting slowly in the final.
"Nevertheless, the team exceeded expectations and will be stronger in 2018 when the tournament is held in Wellington," Maguire said.
The team wished to thanked Sport Whanganui for the use of their van for the trip.
The team included Paul Maguire, Michael Davidson, Jimmy O'Connor, Brad Alexander, Scott Burney, Jason Ditchfield, Russell Eades, Jordan Beech, Josh McDermott, Taco Rangi, Jordan McDonald, captain Brady O'Connor, Paul Miller, Ben Murphy, John McDonald, Craig Thorpe, Matt Roberts, Tom Dixon and goalkeeper Adam Murphy.