Sometimes, happens when both cold engine and when the engine is warmed up. There is sometimes a weird noise when I accelerates. For example I'm cruising at 60Km/H at like 1800 RPMS, and I push on the gas a little harder, raising it to maybe 3000 RPMs, the intake growls when I push the gas, but when I let go of the gas, the engine makes a quite kind of like a flapping noise. Is very quite, but you could hear it. Anyone heard anything like that before? The noise goes away after 2-3 secs. It happens after I push the gas. It rarely happens, but it does happen.

Solution?

 

Probably lifter tick, I wouldn't worry about it.