Daniel Ricciardo used the new engine to secure Red Bull's first pole position since 2013 in the Monaco Grand Prix, and the Australian looked set for victory until a strategic mistake from his team.

While Horner thinks the upgrades to the power unit were worth 0.2 seconds per lap in Monte Carlo, he is optimistic that gain will grow on more engine-dependent circuits.

"I think Renault have done a good job and obviously the gains have come in the power unit," said Horner.

"There has been approximately 0.2s, so hopefully that will translate to a bit more when we get to circuits like Montreal and Azerbaijan.

"It has been a positive step and, without it, we would not have achieved the pole position."

Straightforward deal

After coming close to a divorce last year, Red Bull and Renault announced over the Monaco GP weekend the extension of their partnership until 2018.

The new deal also sees Toro Rosso return to Renault engines after using Ferrari units this season.

Horner said continuing with the French engines was a logical move for Red Bull.

"It was a fairly straightforward discussion to extend the agreement for a further two years," he said.

"With the restructuring in Renault, the commitment they have made, the investment they are making, it was a fairly logical and straightforward discussion.

"It is a competitive price that we are paying and obviously we have that ability to be branded something else and STR taking the same power unit creates further synergies there as well."