He said they were struggling to make the song sound nice and imitates them ,then at some point he started singing with them using different voices to make a complete chorus 

kiekiekiekiekiekiekiekie, Mopao described properly here, i hate his mumbling, i like it when he opens up and tries to sing the higher notes. 

Clearly at this time, Papa Wemba and Kester Emeneya were no longer friends. Mocking Koffi was the truth. Koffi does that mumble nonsense today. We will never know the true reason why Kester left Papa Wemba.

Clearly at this time, Papa Wemba and Kester Emeneya were no longer friends. Mocking Koffi was the truth. Koffi does that mumble nonsense today. We will never know the true reason why Kester left Papa Wemba.

pfffff, everybody knows the reason why Kester left La Musica.
It's was just that he and other musicians were pissed that Wemba wasn't paying them enough.
The second reason for Kester was that Wemba wasn't using him anymore in songs (song like Evemenent, Melina Parisiene & Zea), because Wemba afraid that he could create a band with his fame, which was almost happened one year before with Langa Langa Stars