I'm in the UK and totally agree with you. Having owned several new Porsche's my experience is that having the 14way comfort or 18way adaptive sports seats for example carries more weight on resale than a little bit of leather on the dash.
You also have to bear in mind, that if you claim the full 100% write down allowance, you have to pay it back based on the sale price. Hence why I may not claim the full 100%. I am deciding whether to just claim the 18% or somewhere around 25% in the first year and the 18% annually thereafter.
Hi. I don't find any variation of the loudness of Sports Sound across the different modes. However Sports Mode automatically turns on the brake regen which does have an affect but I can turn this on in Normal mode if I want.