Bob Bell says Renault's exhaust design is within the legal limits as the team explores exhaust blowing in a bid to find performance gains.
Renault raised eyebrows in pre-season testing with the positioning of their exhaust pipe.
That has been directed upwards – by the maximum five degrees – to blow air onto a specially heat-treated rear wing.
"It's no secret there is some benefit from the exhaust flows around the rear wing," technical director Bell told Autosport.
"We've chosen to push our exhaust up as high as you legally can to try to maximise the benefit.
"Different manufacturers have different solutions to that. It's a small gain.
"It's not where it was four or five years ago with blown diffusers by any means, it's nowhere near there, but it's still a useful benefit."