The same engine located just behind you, like the Cayman S, will always be louder than the engine located further behind you, like the 911.

The 1st and 2nd gear ratios in the Cayman S, do hurt a little bit the performance of the car. Comments in several threads in this site expose the believe this was done on purpose so as not to challenge the 911.

Your other impressions are subjective, and I do not have enough experience with the 911 to give you a good answer.

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