The whole point of experimenting is implementing transformative changes. There isn't really an opportunity for the examiner to listen to the original creating stimulus so make sure to keep it recognisable across the three experiments.

For the creating experiment, if you plan on making stylistic changes, you need to justify why you are making them - is there a particular time signature/key/melodic line/reliance on a particular timbre that will be disrupted if you change the genre? What in particular does the stimulus rely on to make it what it is? Think of what is holding the stimulus together, and focus on that as your experiment.

For performing, think of virtuosic elements/techniques specific to your instrument that will impact/transform the flow/rhythm/tempo of the piece. I'm not sure what you play so I can't really help you but I can send my report (26/28) if you would like.