Mat Coch writes:

Mercedes is yet to decide whether to run a revised exhaust layout which it debuted during last week's Young Driver Test at Magny-Cours.

The new layout is believed to be aimed at cleaning up the airflow around the rear of the car, redirecting exhaust gases along similar lines to those used by Red Bull.

However speaking on Thursday in Singapore Norbert Haug was less than convinced that the system would appear on the cars come Sunday's race.

"We need to check it," he cautioned. "Honestly I don't want to make too big announcements because I've learnt over the course of this season that you can only judge it after the practice sessions, after qualifying."

"It was positive in Magny-Cours," he continued, " we did back to backs and that looked like we expected from the wind tunnel, from the calculations from the simulator.

"But these are different conditions here, obviously from the temperatures and so on, and we need to check it here. Ask me Sunday night if we have decided to run it!"

The German was reluctant to brand the exhaust a 'step' forward given Mercedes rivals have also been testing. "You never know what the other guys did," he admitted. "It's a moving target. If you gain two tenths, and the other teams gain three or four or five tenths, then you are quicker, and the others are quicker, but the difference is you are slower.

"You probably get an impression on Friday, but just an impression."

On paper the Marina Bay circuit should suit the Mercedes, which has shown pace on both the Monaco and Valencia streets, circuits which have a number of short, slow speed corners. It's been suggested the Mercedes development exhaust will improve performance around such corners, though it remains to be seen whether it provides the sorts of benefits some sections of the media are claiming.