Another returning Kiwi is Taylor Cockerton, who confirmed his spot on the grid at the last minute.
Despite a lack of preparation the Pukekohe youngster is a fast peddler, and proved that by winning the Formula Masters series in Asia. He might not get as many mentions as Armstrong or Leitch but should be considered a real contender.
Two other Kiwis will make their series debuts in race one.
Ryan Yardley and Reid Harker finished first and second respectively in last summer's Toyota 86 championship. While steering a tin top car is clearly quite different to open wheel cars, the talent was there for all to see with the two youngsters.
Neither should be discounted when looking at contenders as well.
Armstrong's Russian Ferrari stablemate Robert Schwartzman will provide him with plenty of competition and should be among the favourites as also should be returning Dutchman Richard Verschoor, who dominated the first half of last season.
The other internationals to keep an eye on are Brit James Pull and American Cameron Das.
The championship kicks off with race one today before two races tomorrow. Here's what the leading contenders had to say:
Marcus Armstrong
"To be honest I would rather not be considered the favourite but it doesn't really worry me. In my opinion I'm sitting in a good position. Certainly last year at this point I was thinking about how amazing it would be if I was to come back and how much my mentality would be different. This year it seems a lot clearer in terms of what I have to do."
Brendon Leitch
"I have lots of confidence heading into this year and I'm very comfortable in the car. This is my first season after a full year racing overseas and it has definitely helped with my race craft and my comfortability in the car. The goal is definitely to win the championship. There are going to be five or six drivers that are very fast and it will be as, or more, competitive than last season even though the field is a little bit smaller."
Taylor Cockerton
"I am there to win the championship. I have done my two years of learning, my apprenticeship as such. The first goal is to win some races, especially early on in the championship. Obviously it was tough getting a deal done so late - it was hard to prepare mentally for it but I am in the zone now and out there to win some races."
Reid Harker
"Obviously experience counts so those guys with previous experience might be able to get on the pace a bit quicker than us but we get plenty of testing so I am feeling pretty confident. The competition will be as tough as ever - you have three Ferrari Academy drivers and lots of world talent. To be inside the top three or even top five you are going to have to be going pretty quick."
Ryan Yardley
"It is going to be a challenge. I am realistic - I know it is going to be tough but I am ready for the challenge and stoked to be here. The first couple of meetings might be a bit of a challenge. It is about learning and building on the knowledge that I've got and hopefully I can grab some podiums or wins or what not."