Red Bull could lose up to five tenths of a second per lap when the exhaust blowing clampdown takes effect at Silverstone next weekend.
But team boss Christian Horner has thrown a cat amongst the pigeons by saying on Austrian television Servus TV that, until now, the RB7 has only been benefitting from "cold blowing", not the "hot" concept that is so effective when the drivers are off the throttle under braking and in corners.
"In our case, this (effect) happens only with cold-air blowing. Other teams blow hot air and get even more benefit," said the Briton.
If true, Red Bull's key rivals might fall even further away from the pace of the dominant RB7 in Britain and beyond.
"How this affects us compared to the others, we will only see at Silverstone. According to our simulation it's as much as 3 to 5 tenths and perhaps a bit more with some other teams," said Horner.
Former F1 driver Karl Wendlinger said: "I believe Red Bull's superiority will be greater at Silverstone. The (exhaust) system is being banned for all but Adrian Newey is a genius in aerodynamics and this is very important at Silverstone."
But McLaren reserve driver Pedro de la Rosa told EFE news that "nobody has the foggiest idea" how precisely the field will line up in Britain.
The cars will be slower because of the lost downforce
"It will have a strong impact and the cars will be slower because of the lost downforce," he said.
"There is a ray of hope, as we all know which car was the pioneer of the technique and have been able to maximise the performance better than anyone else," said the Spaniard, presumably referring to Red Bull.
At least Timo Glock is aware of the effect that the clampdown will have on his struggling Virgin car.
"We have never benefitted from this technology, so for us, everything stays the same," the German told Auto Motor und Sport.