The Spanish coach says his side have yet to reach their full potential this season and admitted he would welcome some new signings during the January transfer window
The Partenopei extended their unbeaten run at the San Paolo to 16 games courtesy of early goals from Jose Callejon and Marek Hamsik but their Spanish boss was less than impressed by their inability to close out the game, with Lucas Castro's strike having made life unnecessarily uncomfortable for the hosts.
"We are still at 75 per cent," the former Liverpool boss told Sky Sport Italia. "It can improve a lot.
"Sometimes were were a bit unlucky in front of goal, sometimes the goalkeeper was good, but with so many opportunities, we should have closed out the game and I'd have been able to be more comfortable on the bench."
Despite his frustration, Benitez believes that Napoli, who are now just two points behind leaders Roma, are well in the Serie A title race.
"The Giallorossi can no longer hide," he argued. "We also have the Champions League but for the Scudetto there are five teams in the dance. Fiorentina and Inter can also have their say."
Napoli president Aurelio De Laurentiis has hinted at further transfer activity in January, with Maxime Gonalons of Olympique Lyonnais a prime target, and Benitez has admitted that he would welcome some new faces.
"Our squad is good, but Juve has invested for years and thus has an edge," the Spaniard added.
"This summer we lost a great striker [Edinson Cavani], while Conte's squad has many alternatives.
"However, if we work well, we can get closer to Juventus. The president has confirmed that he is ready to intervene if necessary."