Anstey told BBC Sport that his tyre strategy proved decisive in securing the top prize.
BBC: Michael Rutter won the opening Superbike race on Saturday
Anstey had increased his lead by another four seconds by the end of the third lap.
BBC: Anstey pushes his bike to the limit around the TT course
Earlier, Anstey had celebrated his fifth North West win by taking the first 600cc race.
BBC: Robert Dunlop celebrates his 15th win at the North West
New Zealand Anstey did claim wins in the opening 600cc race and Superstock events.
BBC: Robert Dunlop celebrates his 15th win at the North West
Lisburn's Darran Lindsay was the 250cc winner and New Zealander Bruce Anstey triumphed in the Superstock event.
BBC: SPORT | Motorsport | Motorbikes | Ulster GP four-timer for Martin
Caroline Anstey, from the Holme Valley Business Association, said the planned location for the new store was "entirely wrong".
Anstey's win made up for the disappointment of being forced out of Saturday's superbike race after just one lap.
BBC: SPORT | Motorsport | Motorbikes | Anstey secures TT superstock win
Race two saw Lowry beat Amor with Anstey completing the podium and Nutt, Donald and Dunlop the next finishers.
Among his challengers are expected to be TAS Suzuki duo Tom Sykes and Bruce Anstey and former winner Marty Nutt.
"In the first two laps I just put my head down, caught Finnegan and got by him quite quickly, " said Anstey.
BBC: Anstey pushes his bike to the limit around the TT course
Marshall Neill, Bruce Anstey, Gary Johnson and Michael Pearson completed the top six while Toomebridge's Laverty also won both Irish Superbike rounds.
Suzuki will be represented by TAS pairing Bruce Anstey and Adrian Archibald.
BBC: SPORT | Motorsport | Motorbikes | TT organisers boast quality entry
Ballymoney man Archibald won a tight battle for third place ahead of Richard Britton while Bruce Anstey and Martin Finnegan were fifth and sixth.
BBC: Michael Rutter won the opening Superbike race on Saturday
Hutchinson atoned for his late mistake in the Superstock race by taking an impressive win ahead of Frost, Anstey and Carrickfergus man Alistair Seeley.
BBC: Robert Dunlop celebrates his 15th win at the North West
But Enniskillen man Britton closed the gap and kept up the pressure on his Honda machine, only for Anstey to hold on for the victory.
BBC: Michael Rutter won the opening Superbike race on Saturday
"The week started off badly - to be honest I was gutted, " said Anstey, who was riding for the Northern Ireland based TAS Suzuki team.
BBC: SPORT | Motorsport | Motorbikes | Anstey secures TT superstock win
Anstey beat the lap record twice, posting a best new time of 128.40mph, and he also broke the race record by more than a minute.
BBC: Anstey pushes his bike to the limit around the TT course
Ian Hutchinson, Bruce Anstey, Guy Martin, Adrian Archibald, Martin Finnegan, William Dunlop and Ryan Farquhar are among the other big names expected to compete at the meeting.
Anstey's TAS Suzuki set a lap record for the class of 116.74mph to win ahead of runner-up Les Shand from Scotland with Ian Lougher of Wales in third.
BBC: Robert Dunlop celebrates his 15th win at the North West
There was no letting up by Anstey on the final lap, and again he was fastest round the course to the delight of the travelling contingent from New Zealand.
BBC: Anstey pushes his bike to the limit around the TT course
Bruce Anstey had a disappointing season by his high standards, although he did win the feature race at the North West 200 and the Superstock TT in somewhat fortuitous circumstances.
BBC: SPORT | Motorsport | Motorbikes | Lougher's experience is decisive
After the first lap, Anstey's lead was already 13 seconds, and it was pushed out to 23 seconds after lap two when the Kiwi bettered his new lap record by almost a second.
BBC: Anstey pushes his bike to the limit around the TT course
Nine people were rescued off Redgate Beach in Torquay following several injuries including a dislocated shoulder and in November two instructors received leg injuries at Anstey's Cove while scouting for new coasteering sites.
Anstey showed his intentions from the outset by setting a new lap record of 17 minutes, 38seconds on the opening lap, a fact made even more remarkable given it was from a standing start.
BBC: Anstey pushes his bike to the limit around the TT course
After the lead had changed several times, Hutchinson seemed likely to win the race in the closing stages but the Englishman went wide at the final chicane which enabled Anstey and Porter to sneak through on the inside.
BBC: Robert Dunlop celebrates his 15th win at the North West
The Woodhall Spa rider finished ahead of Bruce Anstey in the first race although it ended amid confusion with the officials failing to wave the chequered flag which led to Plater and Anstey continuing to ride hard for over half-a-lap before realising that the race was over.
BBC: Robert Dunlop celebrates his 15th win at the North West
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