What is engine power of Benelli TNT 600?

Depends up on your need , but it is one of the good sounding bike of this range. cost around 4- 8 k depends upon the way you use bike. but mind-it, it is not utility bike hence service may not be cheap.

The fuel overflow problem is not , linear/often , it may be with certain batch of bikes. But the Honk problem is common, you can check in any good forum.- I have been using it for past 3+ years and trust me, the engine quality is awesome ,that sound is awesome and comfort is good in city rides and long as it is necked bike. the bike is made up of good materials.- but since it is 4 cylinder bike it heats a lot - it is heavy

First you tell me what is your purpose if you need sound and you like a L line 4 cylinder engine then my suggest is you go for benelli 600i otherwise as a bike performa Ninja 650 is better than benelli 600i