Supercars has mandated the parity change off the back of a first round of formal Centre of Gravity testing with the new-spec cars earlier this month.
While the change isn't expected to yield a massive difference in lap time, with the prediction around 0.006s per lap at Wanneroo Raceway, van Gisbergen says he doesn't see the change as insignificant.
He also expressed some confusion that the messaging from Supercars, which first spruiked how close the results of the CoG test were before mandating the change later.
"I don't think it's insignificant," he told Motorsport.com. "It's going to be there.
"It seems weird to change something by a millimetre and a half when the email went out with the results saying the result could have had up to a millimetre worth of error.
"I really don't get it. But if it silences the party stuff and makes the optics of it better, you understand it."
The CoG change is one of a number being made to the Gen3 cars for Perth this weekend along with a revised catch can breathing system as a fix for the engine fires seen at Albert Park.
Chassis strengthening work has also been green-lit by Supercars to improve the repairability of the new cars.
According to van Gisbergen those changes, combined with the unique short, fast Wanneroo layout, makes it difficult to predict the form heading into the weekend.
"It's just another unknown for the season," he said. "It's a completely different track to where we've been, and then [Symmons Plains] is different again.
"That's the exciting thing and the challenge. We'll be going [to Perth] with quite a different set-up to what we've run before [and] no idea where we're gong to be, or what impact this Centre of Gravity stuff will have.
"That's what makes it exciting I guess. You've got no idea what's going to happen."
Practice for the Perth SuperSprint kicks off on Friday.
