"So, why not?"
The driver sneaked past the race leader during the race restart, after getting side by side with Daruvala on the run to turn one, before emerging with the lead of the race on the other side.
"[The move] was instinctual. You can't plan a move like that," he explained.
"I did what my feeling was - I tried it, and I was in a position where I could pull out if Jehan [Daruvala] came over. But it wasn't too risky in the end in my opinion.
"A lot of people have been saying that it was, but I didn't see it that way."
Having claimed the maiden race win, Armstrong now says that the championship crown is in his sights.
"Absolutely. It's a championship. To me, I'll be honest, I'm not going for these cups or trophies or anything in particular. I'm looking for the points and a consistent run," he said.
"At the end of the weekend, [they're] just another race for points."
Rounding out the podium behind the battling leaders was Red Bull Giles Motorsport racer Richard Verschoor. Thomas Randle and fellow New Zealander Taylor Cockerton rounded out the top five, while the third of the Kiwis, Brendon Leitch, took ninth place.
The Castrol Toyota Racing Series have two more races at Mike Pero Motorsport Park tomorrow, with the prestigious Lady Wigram Trophy to be decided tomorrow afternoon.