Wing Kris Palmer scored the first try 25 minutes into the game, converted by Richard Apanui.
Towards the end of the first half Horowhenua Kapiti had a spell pushing on the Coast line, and prop Cameron Scott scored a pushover try, converted by No.10 Brandyn Lawson, and making the halftime score 7-7.
East Coast had the strong southerly wind behind them in the second half, and Apanui put this to good use by kicking a penalty from halfway soon after the break, followed by another from 48 metres.
The Coast continued to dominate the first 25 minutes of the second half, increasing their lead to 20-7 with a try to lock Hone Haerewa, converted by Apanui.
Horowhenua Kapiti’s outside backs were confined by the Coast defence for the whole game, but a determination to win came from their forwards. Leading the charge was captain and flanker Antony Fox, who scored the first comeback try after 30 minutes.
This was followed by another period of pressing on the Coast line, and a try to prop Ulu-ki Ha’amea.
Lawson scored and converted Horowhenua Kapiti’s last try.
East Coast coach Willie Waitoa had the backline he has been wanting all year, with first five-eighth Richard Apanui back from injury and combining well with halfback Sam Parkes, and later Charlie Harrison, as well as the outside backs.
Asked about the Coast team’s tunaround, Waitoa said: “It’s all about effort, and we had that right from the start.
“Also, having Richard (Apanui) on the field was a large part of the puzzle, working with Courtney (Mita) and TK (Moeke), who had great games.
“The boys just kept slogging away. Our forwards’ first-up tackles pinned them down, with Donny Mill playing extremely well. I was also impressed with prop Antony Tuahine — it was his first start and he has certainly put his hand up.”
Horowhenua Kapiti 24 (Cameron Scott, Antony Fox, Ulu-ki Ha’amea and Brandyn Lawson tries; Lawson 2 con).
NGATI POROU East Coast 20 (Kris Palmer, Hone Haerewa tries; Richard Apanui 2 con, 2 pen).