Nico Hulkenberg reckons there is "even more" in his VJM08 after Force India finished near the front of the timesheets at Monza.
Hulkenberg and his team-mate Sergio Perez, powered by a superior Mercedes engine, had a great opening day for the Italian Grand Prix weekend.
The duo were fourth and fifth in both practice sessions on Friday, with Hulkenberg ahead of Perez in the morning before dropping behind on the soft tyres in the afternoon.
The team-mates were separated by less than a tenth of a second.
"That's not bad at all," was Hulkenberg's assessment on Friday evening.
"The car had quite good pace today and we collected a lot of information about the tyres on the long runs.
"We lost a little bit of track time when I had to cut short a run in FP1 and return to the garage, but in the end it wasn't a problem because we got nice long runs done on both tyre compounds.
"We were also able to test all the new items we wanted to try out, which was very positive, and now we're just going to do the usual tweaking overnight to get even more out of the car and improve the balance further.
"Overall it was a very good, straightforward, useful and productive Friday."