You can get pretty much any premium equipment installed on a lower trim level model, but it usually costs a ridiculous amount by the time you pay retail for the part plus dealer install. But as part of a negotiable purchase deal, you can sometimes ask for some up-level goodies in the deal, if you aren’t seeing eye to…

Some manufacturers warn against this, especially if there are seat mounted airbags. In a seat equipped with side bags the upholstery, stitching etc is all designed to break in a certain, controlled way. Re-upholstering the seats in leather can change these characteristics. I am not aware of any injuries attributable…

There you go. One galactic race down. 4x more to go.