Trevor Carlin says his team was satisfied with its first day of IndyCar oval testing but that his drivers were "shocked" by the reduced downforce from the new aerokits.
Charlie Kimball and Max Chilton finished Friday's first day of testing at Phoenix 15th and 18th respectively, both recording more than 100 laps in the process.
Carlin said his team had been affected by "software gremlins" but that those had been sorted by the end of the first afternoon session and "the second session ran really smoothly" afterwards.
But the team owner said both Kimball and Chilton, who have seven and two years of experience in IndyCar respectively, were startled by the "sketchy" handling of their cars on the oval with the new for 2018 aerokit.
"It was a bit of a shock for them, their first time on an oval with these cars," he said.
"They'd heard all about the 40% loss of downforce but didn't realise the cars would still be so quick - roughly the same lap times as last year, but with a different way of making that speed.
"I think they were surprised by how sketchy the cars are. You can't carry as much speed in, so you're starting the corner sooner, getting the work done earlier.
"We started off with a baseline and then started the fine-tuning, and I think we made a bit of progress.
"It's like any championship when you first come in - you turn up, get a feel for the cars, and then start getting yourselves competitive. That's our next step."
Carlin also praised the quality of the IndyCar package.
"The front part of the car, in concept, is almost exactly the same as Dallara's IL15 [Indy Lights car], and then the rest of it is really well put together," he said. "[It's a] great gearbox from Xtrac.
"And then a fantastic engine - Chevrolet and Ilmor have done a lovely installation, too.
"Although we're new boys here, they couldn't be more professional, and they're working really well with us."