Sports broadcaster and PNBHS old-boy Hamish McKay, who is based in Auckland, tweeted in astonishment after last Saturday's result: "PNBHS were having a pretty good season until this! Beat Grammar up here etc. 100 nil. I'm not sure I'll ever move on. HBHS on another planet."
Individual star of the show is wing Kini Naholo, brother of Super Rugby star and recent All Black Waisake Naholo, who has 28 tries to his credit this season.
It's sent some school rugby followers searching the record books for the record number of tries scored by a player at top first XV level.
But team manager Jason Bird says the teenager is concentrating only on the team game, and his schooling.
As it happens, Napier Boys' High, the favourites in the inter-school clash most years, haven't been doing too badly either and in 12 games were beaten only in the "pre-season" phase.
Their strength, says manager Dave Russell, is defence, for they've conceded only nine tries.
But he says it's a comparatively inexperienced side, with several new to first XV rugby this year.
They rounded off preparation for the local derby with a 39-5 Super 8 first round away win over Gisborne Boys' High last Saturday.
There were no chest-thumping predictions for the game which, according to MetService forecasts, will be played in near-perfect conditions.
Mr Bird expects it to be as close as any of the Hastings-Napier clashes over the years, with the margin usually little more than four points.
Mr Russell, perhaps tipping the hat to those claiming there's an invincible team coming from the other side of the Tutaekuri, says: "They're playing a pretty attractive game. We just need to hold on to possession, for long periods of time."