Formula 1's governing body, the FIA, has issued a new directive aimed at restricting the use of special engine modes for the purpose of increasing exhaust gases for aerodynamic benefit.

The use of the air flow from the exhaust to increase downforce at the rear of the car is nothing new and has seen F1's rulemakers consistently try to limit such concepts.

After switching to a single exit pipe in 2014 to banning monkey seats for this year, teams do still focus on using the exhaust for aerodynamic gain with Renault the most notable due to their angled exit pipe towards the underneath of the rear wing.

Speculation now hints that Ferrari has a unique system but only with Sebastian Vettel as the German has a third paddle located on the back of his steering wheel, while Kimi Raikkonen does not.

A former member of the Scuderia and now the head of single seaters at the FIA, Nikolas Tombazis, responded with the latest directive ahead of this weekend's Azerbaijan GP.

“We do not accept that engine modes specifically designed to increase the exhaust flow in corners are permissible," he said in a message later revealed to the media.

“To be permissible, such flows should be the result of settings that genuinely increase the performance or reliability of the power unit, and not contrived to increase the exhaust flow.”

With no way of completely regulating the matter, Tombazis claimed all related matters would be dealt with on a "case-by-case basis", however, an effort is being made to make the issue completely irrelevant for next year.

“For 2019, we intend to overcome this issue by acting on the exhaust position,” he revealed. “This matter was discussed in the last TWG [Technical Working Group], but we do not feel that a sufficient solution was found.

“Hence, we intend to have a discussion on this topic in the next TWG, with the aim to achieve an exhaust position that clearly prevents any direct aerodynamic gain, thus eliminating the need for checks on engine modes.”

On a separate topic, the FIA has also given the go-ahead for teams to mount their mirrors on the Halo cockpit device given certain criteria are met.

“We expect that you will be able to satisfy us that the installation is sufficiently rigid to ensure that the mirror does not vibrate too much, which would limit driver visibility," a separate directive read.

“We will not accept a dual mirror mounting (halo and traditional survival cell), as this could cause delays in the event a rescue team had to remove the halo following an accident."