Lazy/slow actuator or wastegate?

[JJtheHITMAN]

The variation off harshness in boost is alot, even passengers iv had have noticed, the lag is always the same, power wise and spool time wise. when i boost if i lift off and back on the throttle sometimes more boost can be achieved, my reasons for thinking either a lazy actuator or sticky wastegate (which i forgot to previously mention) is lately iv noticed a metallic jingling which sounds like the exhaust on idle which iv come across before and turned out being an insecure wastegate? What other turbos would be a staight swap with mine then? That require no mods to fit?