The ongoing Supercars parity debate is set to step up another notch when the series heads to the high-speed Phillip Island circuit this weekend.
Holden finally broke through for its first win of the season when Shane van Gisbergen won on Sunday at Symmons Plains.
It ended a streak of seven consecutive wins in 2019 for the new Ford Mustang, with reigning series champion Scott McLaughlin winning six of them.
After the first event in Adelaide, the pace of the Mustang concerned Triple Eight boss Roland Dane, who suggested the new-for-2019 model has an 'unfair advantage'.
MORE: Everything you need to know about the 2019 Supercars season
Last weekend's Tasmania event featured some key changes - notably, parc ferme conditions between qualifying and the race were in play in a bid to shake up the grid.
However, the lead-in to the Tasmania event was dominated by the parity debate, which forced Supercars to hold a centre of gravity (CoG) test to see if the Mustang held an advantage.
It was discovered that the Mustang and the Holden ZB Commodore held an advantage versus the Nissan Altima - as a result, ballast was repositioned in both the Mustang (28kg) and the Commodore (6.7kg) prior to the Tasmania event. Ford teams happily yet hesitantly agreed with the changes.
The CoG test levelled the playing field to a certain extent at Symmons Plains, but Phillip Island - the flowing grand prix circuit that also held the pre-season test - will play another key role in the parity debate, with data from the weekend crucial to finding more answers.
While the Mustang got the tick of approval and was homologated ahead of the 2019 season, questions now remain over the process - and Walkinshaw Andretti United co-owner Ryan Walkinshaw said that it may take a "year of pain" for Supercars to realise certain errors in its approval process.
"I think it's important that the sport, and all of us as teams together, explain why it happened the way it did and be honest and say that the previous processes allowed the Mustang to be approved," Walkinshaw said on the Below the Bonnet podcast with drivers David Reynolds and Michael Caruso and Motorsport.com journalist Andrew van Leeuwen.
"[That's] if it has an aero advantage, we still don't know... it was fit-for purpose for what we used to have, but there's been a dramatic change in the body shape of the new vehicle that's come in.
"The current and previous process probably isn't up to scratch, and we need to do a better job.
"We need to come up with a new process that's more accurate so in the future, we don't make any mistakes."
Ford driver Fabian Coulthard said after his team's 1-2 finish on Saturday that while the changes have slowed the Mustang, it simply proved his team is doing a good job: "I wouldn't say it hasn't affected us... but we're just doing a better job and have got a handle on it."
Seven-time series champion Jamie Whincup was convinced there are more testing plans in the works - but that'll come at a cost.
"There's going to be a lot more testing that goes on over the next three or four months from Supercars, some proper high-quality stuff," Whincup said after Friday practice in Tasmania.
"They're going to spend a fair bit of money to guarantee that all three models are exactly the same. Which is welcomed by everyone, because then we can stop talking about it and whoever is standing on the top step of the podium is genuinely the best team.
"I think we've just to hang in there. Mistakes have been made, if you know what I mean."
Because physical wind tunnel testing is banned, Ford Performance performed much of the computational fluid dynamics (CFD) work on the Mustang Supercar in the US. However, fans and pundits were quick to call out the Mustang's funky look when it initially broke cover.
Walkinshaw refused to take credit away from Ford teams Shell V-Power Racing (Dick Johnson Racing-Team Penske) and Tickford Racing, who with the American-based Ford Performance, helped develop the Mustang-spec Supercar.
Regardless, Walkinshaw suggested existing processes need to be tweaked to ensure total parity can be achieved moving forward.
"We shouldn't take anything away from the work they've done. They've done it - from my understanding - within the rules, and it got approved," Walkinshaw said.
"They have a fair argument to say, 'hey guys, shut the hell up, that was the process, you approved it, get on with it for this year, suck it up'.
"If I'm thinking about the sport and the fans, maybe we need to take a year of pain, and maybe that's punishment for not having a better process in place in the first place.
"Going forward, we need to be 100 per cent sure that the cars coming on track have got aero parity, and we've got to be 100 per cent sure that they've got CoG parity, 100 per cent sure they've got parity over the maximum output of the engines and so on.
"That's what gives us exciting racing. If we want to be a parity series, that's what we need to do.
"If you don't want to be a parity series, go and watch Formula 1, and enjoy having budgets that kill teams. We're not a country that can support that kind of racing category."
