Under the late evening floodlights at Barbagallo, the 17-year-old How moved from fourth on the grid into the lead following the pit stop sequence.
He then saw off a determined charge from stable-mate Geoff Emery to win a nail-biting encounter.
How slotted in behind Emery in fourth at the start, circulating in the slipstream of the two-time champ’s Valvoline Audi R8 LMS Evo.
A three-way battle for second place developed with Peter Hackett leading the group in the Eggleston Motorsport Mercedes-AMG GT3.
How was the first into the pit lane when the compulsory pit window opened, the BTE Bulk Transport Equipment driver stalling as he went to pull away.
Losing a handful of seconds as he re-fired the car, How rejoined the race in tenth as the remainder of the field began to peel into the lane.
Opting to serve their stops late in the window were the two Mercedes-AMG GT3 entries of Mark Griffith (Nineteen Corporation) and Max Twigg (WM Waste).
Twigg had risen to the race lead, and returned to the fray in third behind How and Emery while traffic for Griffith in the laps prior to his stop hurt the Queenslander’s quest.
Hot on Twigg’s tail after the stops was Hackett, setting up a thrilling duel that lasted until the chequered flag, Hackett stealing through to the final podium spot inside the final ten laps.
A spirited drive from pole-sitter Peter Major saw the Totally 4×4 Wheels Lamborghini extend a small advantage in the opening laps, before falling to ninth during the pit sequence.
The local favourite then stormed back to fifth at the flag, shattering the race lap record by 1.7 seconds in the process.
There were nose to tail battles throughout the field, with Dale Paterson (Dale Paterson Motorsports Chevrolet Camaro) and Scott Taylor (Scott Taylor Motorsport Porsche 911 GT3 R) fighting over eighth place in the opening laps.
It was a battle won by Paterson, who was the second Trophy Class runner to the line behind How, with Taylor taking third in class.
The race’s only two-driver pairing, Justin McMillan and Glen Wood, took top honours in the GT4 class, the M Motorsport KTM X-Bow heading the sister Vantage Freight entry of David Crampton.
Nick Kanaros topped the Trofeo Challenge Class, the Earth Electrical Contractors Porsche 911 GT3 Cup car heading Jim Manolios in the Haemokinesis/Trofeo Motorsport Lamborghini Super Trofeo.
Victory for How will see the Victorian teenager start in pole position for Race 2, which gets underway on Saturday at 1545 local time.
Ryan How, BTE Bulk Transport Equipment Audi R8 LMS – 1st
“It’s hard to describe what it feels like to win. I’m just so happy, I’m super stoked!
“The start went really well, everything was nice and easy; no-one was pushing and shoving. Then I just stuck to consistent lines and kept the lap times coming until the pit stop.
“It was really good following Geoff Emery and Peter Hackett, seeing different lines and how they actually race, which was a really good experience – I was just doing my best to keep up with them.
“I came out of pit lane and it was clear for a bit until I got some traffic, then I got told on the radio ‘Geoff’s behind you, just be cautious’.
“It was then a matter of who got through the traffic and how lucky you were when you caught them.”
Australian GT Championship: Round 2, Race 1
Pos Team Driver Car Class Laps Time
1 BTE Bulk Transport Equipment Ryan How Audi R8 LMS Ultra TR 42 43:18.243
2 Valvoline Geoff Emery Audi R8 LMS EVO CH 42 43:22.392
3 Eggleston Motorsport Peter Hackett Mercedes-AMG GT3 CH 42 43:33.825
4 W M Waste Max Twigg Mercedes-AMG GT3 CH 42 43:34.660
5 Totally 4X4 Wheels Peter Major Lamborghini Gallardo CH 42 43:44.141
6 Nineteen Corporation P/L Mark Griffith Mercedes-AMG GT3 CH 42 43:44.216
7 Haemokinesis / Trofeo Estate Ryan Millier Lamborghini Huracan CH 42 43:56.839
8 Dale Paterson Motorsports Dale Paterson Chevrolet Camaro GT3 TR 42 44:14.917
9 Scott Taylor Motorsport Scott Taylor Porsche 997 GT3 R Cu TR 41 43:31.230
10 Aaron Laboratories Joseph Ensabella Porsche 997 GT3 Cup TR 39 43:30.989
11 Earth Electrical Contractors Nick Karnaros Porsche 911 GT3 Cup TC 39 43:31.851
12 M Motorpsort J.McMillan/G.Wood Reiter KTM X-Bow GT4 39 44:14.539
13 Safe-T-Stop Richard Gartner Lamborghini Gallardo TR 38 43:51.485
14 Vantage Freight / M Motorsport David Crampton Reiter KTM X-Bow GT4 37 43:42.968
15 Haemokinesis / Trofeo Estate Jim Manolios Lamborghini Super Tr TC 36 43:27.048
Source. Australian GT