Jorge Lorenzo says the new aerodynamic fairing Ducati introduced ahead of last weekend's MotoGP Czech Grand Prix has provided a step of half a second.
The Spanish rider trialled the new bodywork during Friday practice at Brno and used it for the rest of the weekend, including the race, saying it improved his front-end confidence.
Despite finishing 15th in a rain-affected 'flag-to-flag' race after his second bike had not been prepared by his crew at the time of his pitstop, Lorenzo said he felt using the fairing had produced a notable performance gain.
"The key is that I'm getting to close to the feeling I had with my previous bike," said Lorenzo.
"I don't have it yet, but it will come. The fairing gives me a lot of confidence in the front.
"Let's say my limit is farther. I am faster, half a second faster on all laps."
The new fairing was part of a larger homologated design that Ducati brought to the first race after the summer break, which Pramac rider Danilo Petrucci used during Saturday's third practice session.
Lorenzo had a chance to sample the full bodywork on Monday during post-race testing, but said there was little difference between it and what he had used during the race weekend.
"I tried the other option on Monday, I didn't try it during the weekend, because we knew it didn't change so much," he said.
"It has a little bit more affect, but you lose more speed on the straights.
"From the old fairing to new fairing, you feel 80% to 90%, the other one [new parts] is just 10 %.
"Petrucci tried it, but discarded it.
"He didn't use it. For him it was worse.
"So it depends on your riding. If it was clearly better for him, he would use it. He's not stupid."
Lorenzo's factory Ducati team-mate Andrea Dovizioso did not use the new fairing at all during the Brno race weekend, but tested it for the first time on Monday.
The Italian said he was planning to at least start this weekend's Red Bull Ring event with the fairing.
"I think we will start [with the fairing]," said Dovizioso.
"But only when we get on the track we will understand exactly the positives and negatives.
"We used the test in Brno to understand the best way, to have the right feedback from the new fairing.
"It was quite clear what we tried on that track.
"We will see in the future how we will use that, but I believe on this track it's positive to use."