The standard air filter, even when quite dirty, will flow more air than the engine can ever need. It will also do a better job at keeping grit out. If a cone filter was better, Fiat would have fitted one.
Save your money for essentials, like brakes, steering and suspension. And I don't mean modifications.
Also, if you fit a cone filter, it is a modification. You have to declare it to your insurance company, and your premium will increase. If you choose not to declare it, if you have a bump, you may find yourself in a lot of trouble when your insurance company abandons you.