Roestenburg said the top five players in the team were all unbeaten over the weekend, winning most of their matchups in three games.
Pakistani ex-pat Hamzi Ali was especially outstanding.
Roestenburg said several of the players had progressed so rapidly to D-grade that some had made C-grade by the time they appeared in the E-grade nationals.
The championship will be held in Wanganui on August 21-26.
"We expect to completely pack the gallery with supporters decked in Wanganui gear in August so that will be a great spectacle," said Roestenburg.
"Superchamps squash is the only squash competition where the crowd goes a little nuts just like Davis Cup tennis so expect some fireworks then."
Wanganui's women were not quite as successful in New Plymouth, finishing fourth in the six-team competition, which was their pre-tournament seeding.
Roestenburg said they were unlucky to lose some close matches in a tight draw.