Reja can see Napoli being transformed under coach Antonio Conte.
Reja told Radio Kiss Kiss: "Napoli is growing and the draw in Turin (at Juventus) also shows it. On a tactical level I liked Napoli much more than Juve, the Azzurri players looked for something more.
"Few total goal opportunities, but seeing a healthy Napoli with great personality made me happy. I thought they would opt for a 3-5-2 and surprisingly they played with 4-3-3.
"(Scott) McTominay is a great purchase, then I really like (Alessio) Buongiorno. They have given Napoli important values. If Napoli reaches the top of the table then it will be difficult to catch up. Let's wait for the fifteenth day of the championship and then we'll talk about it again. Also because Napoli's calendar is tough between the tenth and fifteenth.
"We have seen that the team is growing in mechanisms, in harmony and I still expect further improvements. There will be the insertions of new players, Conte's mentality will be decisive also because it gets inside the players' heads.
"You don't mess around with Conte and I'm sure there won't be any drops in tension with teams like Monza or Como in the next matches. Conte creates a thousand problems because nothing ever goes well for him. The players who have now created all the conditions to see a great Napoli."