I find the wastegate shh's have it's own character and react differently to throttle differences at the time of gear change.
For example if i sort of double or triple press the throttle when changing gears you get the staggered shh shh shh pop bang, but with a solid throttle press you get the...
Their is a tool available from somewhere (I know very helpful(
A small flat head screwdriver and pliers did the trick for me.
Putting them back on needs to be more tactile tho... I used a right sized socket bit to push them evenly and then some pliers to finish.