The team is turning its attention to securing a home final next month after 4-1 and 6-2 victories at the Queenstown Ice Arena on Friday and Saturday nights.
Coach Adam Blanchette said his players kept their composure on Saturday when the scores were tied 2-2 after the first two periods.
With the Stampede making more than twice the number of shots on goal, Thunder goalie Kane Easterbrook had kept his team in the game for the first two periods.
But he was always confident the Thunder would eventually crack, Blanchette said.
''We've got a team of veterans, and you learn how to win those games.''
Doing much of the damage for the Stampede was Colin McIntosh, who finished with a hat-trick.
The team would now focus on league-toppers and finals opponent West Auckland Admirals, whom it takes on in Queenstown this weekend.
''We've got a pretty big weekend coming up. We want to get that home final - it would set us up if we take both games off them.''
Although the Stampede had six regular-season games remaining before the finals, there was no danger of the players switching off mentally.
Their desire to win a third consecutive Birgel Cup would guard against any complacency, he said.
''You don't become complacent - you can sit back at the end of the season and reflect on your accomplishments.
''It's nice to know we're in the finals, but we know we should be there. We want a home final and we want to lift that cup.''
The Admirals' emergence this season, which has kept the Canterbury Red Devils out of the finals for the first time in eight seasons, had come as no surprise.
People were forgetting the Admirals were only one win away from the finals last year, he said.
''They're a younger team that are starting to become veteran players in the league.
''They've also got a good crop of imports this year.
''It's great for the league.''
