Mini Cooper or S

….I can’t decide! There is a purchase of a convertible automatic and now we are at the superior COOPER and tuning or S without tuning What are the experiences and where can I find a serious tuner which also replaces the factory warranty? Does Carlson also do something at Mini? Where can you get beautiful attachment parts? How does the automatic drive in the Cooper and S ? Many questions……lover before than later too late! Thank you and greetings