Tauranga Boys' led 17-10 at halftime, with mobile lock Mitch Holton grabbing a brace of tries. New Plymouth based their attacking plays around second-five Legend Campus-Newton, but once he was shut down, so too were their options.
Both teams scored early in the second half to have the game poised evenly at 24-17, before Tauranga Boys' Harris Williams, Kelly and Salesi Leota scored tries to complete the rout of their long-standing traditional rivals.
"We were wounded, we were down on numbers, and for all the guys that don't play a lot to step up and put in a convincing one was very good," said Tauranga Boys' captain Fifita. "They have given a few of the starters a run for their money.
"We are happy with our start to the Super Eight. Last year we began with a win over Rotorua but couldn't follow it up, with six losses after that. That was the big talk going into this week, saying that we wanted to follow up a good performance and this was our last home game for a while, so we thought we would put on a show."
Tauranga Boys' play Napier Boys' High School away next Saturday.
Tauranga Boys' College 41 (Mitch Holton 2, Christian Kelly 2, Leighton Hika, Harris Williams, Salesi Leota tries; Carlos Price 3 cons) New Plymouth Boys' High School 17 (Michael McDonald 2, Liam Rowlands tries; Brayton Northcott-Hill con). HT: 17-10.