Honda "will completely close the gap" to top engine manufacturers Mercedes and Ferrari in 2019.

That is the prediction of Franz Tost, the boss at Toro Rosso.

The junior Red Bull team has been powered by works Honda engines for a full year now, in preparation for the senior team to join the Honda project for 2019.

"Since we will use the same engine, there are many other synergies," Tost told Speed Week.

"Toro Rosso will use the Red Bull Racing gearbox, full rear suspension and front suspension elements and other parts," he revealed.

"We will save resources and expect an increase in performance."

The rhetoric from the entire Red Bull camp is extremely positive about the switch to works Honda power, after years of complaining about customer Renault engines.

"In terms of performance, Honda has narrowed the gap to Mercedes and Ferrari," Tost said.

"If no serious problems arise in the next stages of development, Honda will completely close the gap during the 2019 season."

Ferrari, Force India and Renault have already announced mid-February launch dates for their respective 2019 cars -- just days before winter testing begins in Barcelona.

Tost said of Toro Rosso's 2019 car: "The rollout is planned for week 7 (mid-February). We are current discussing various scenarios for the presentation."