What is the best modification to do on a car, if you could only choose 1?
Stripping the interior. It's always been the first thing on my list.
You must be a really tidy minimalist sort of person then!
Comfort is overrated.
Upgrade to fully comp Insurance and learn how to drive properly not just pass a test that is based on being less stupid than others.
Being taught how to handle a car correctly will far outweigh any other first mod.