Mr Mischewski said it was still too early to say what petrol would cost, but Gull's arrival would bring genuine competition and force other service stations to lower their prices.
"Wherever Gull turns up, lo and behold, prices drop," he said.
Last week the price gap between Kerikeri and the cheapest outlet in Whangarei, which has some of the sharpest petrol prices in the country, was more than 30 cents a litre.
The AA puts that difference down to what it calls "the Gull effect", with a Gull service station at Otaika forcing other fuel companies to drop their prices.
Proximity to the Marsden Pt oil refinery is not a factor because Gull's petrol is transported from the port at Mt Maunganui.
Gull earlier told the Advocate it had chosen Waipapa for its growth prospects and role as a retail hub.
It was unlikely to open any outlets further north because of the distance from Mt Maunganui.