The Moto2 title contender started the testing programme that will lead to his 2017 MotoGP graduation with two days of running at the Italian circuit.
"When I twisted the throttle the speed I could feel was incredible," Lowes said of his first impressions. "It was a brilliant feeling.
"On the second run, I had already begun to manage the power better and I tried to understand how to take the best advantage of it.
"There were a lot of new things to discover and they all astonished me.
"The first ones were definitely the power and speed, and then the carbon brakes.
"The third is the seamless gearbox, which is really incredible, and the fourth is obviously the electronics, which I felt comfortable with straight away.
"And then the RS-GP surprised me with an agility that I hadn't expected, so much that the night before the test I was quite nervous because I was imagining a much harder bike to ride, but that's not at all the way it was, although nothing is easy on a MotoGP bike."
Aprilia's racing manager Romano Albesiano was impressed with how the 25-year-old adapted to a MotoGP bike from the outset.
Further tests are planned for Brno and the Red Bull Ring around his Moto2 title bid, which continues at the Sachsenring next month.
"I'd say that we could not have had a better start," Albesiano said.
"Sam got on a bike that he had never seen before, having to deal with a series of new features that range from the available power to the carbon brakes.
"He was at ease straight away and he also proved to be very analytical and precise in the indications he gave the team, as well as with his work method.
"Naturally, we were not looking at times, but even from this point of view we are quite pleased with these two days."
He added that di Meglio focused on "new chassis parts and working on the electronics, especially in terms of torque output" for the RS-GP.
Lowes will be joined at Aprilia in 2017 and '18 by outgoing Suzuki rider Aleix Espargaro.
Source : https://asia.eurosport.com/moto/lowes-astonished-by-motogp-aprilia_sto5669306/story.shtml