The Florence side go into the match at the Artemio Franchi stadium on the back of three straight wins in all competitions.
Last weekend's 2-1 triumph at Chievo followed their 4-2 victory over Juventus and lifted the Viola to fifth place, level on 18 points with Inter Milan, who are fourth.
"I am extremely happy," Montella said.
"With respect to last season I see a team that is more precise and convinced of its strength.
"We are scoring more than we were last season and we are adapting better to our opponents.
"I don't know where this will take us but what I do know is that we are growing and we have to continue on this path."
Fiorentina have lost just once this season, a 2-1 reverse at Inter Milan, and remain unbeaten at home.
They take on AC Milan at the San Siro this weekend, but will first be put to the test by a Napoli side that is showing few signs of slowing down.
Rafael Benitez's troops bounced back from their 2-0 defeat at Serie A leaders Roma with a 2-0 triumph over Torino last time out.
Gonzalo Higuain's two goals handed Napoli their seventh win of the campaign and kept the Azzurri in second place, five points adrift of Roma.
"The important thing was to return to winning ways," Higuain said.
"I am happy for the goals but even more delighted for the three points.
"Now we have to prepare for a difficult game in Florence and hope we can bring home a win."
Fiorentina have scored 19 league goals in nine games already, but their attack will be tested by a Napoli side who have given away just six goals.
Giuseppe Rossi, who is Serie A's top scorer with eight goals, will lead Fiorentina's forward line. The hosts will be without suspended defender Gonzalo Rodriguez.
Napoli's Giandomenico Mesto, Valon Behrami and Jose Callejon are set to start having been benched against Torino.