Chain slapping like noise
 

Hey guys, a weird problem has developed where at about 2000-2100RPM and 3000-3200RPM, there's a chain slapping like noise, sounds like a cam chain type motor where the chain is loose and slapping about.

Its quite audible but sounds different from the engine bay as opposed to inside the cabin, my interior is gutted also so I hear alot of noise from the bay.

Anybody have any idea what it could be?