Buck, I think that anything a person owns should be customized/personalized. It's easy to let corporate manufacturers dictate what the public is suppose to want, but only a true individual knows what he/she wants. Whether you build a full blown custom or add a horn to your bike, only then do you make it your own! Put your Freak on it!
I sometimes get confused as to how people differentiate between the words 'original' and "restored" and "custom". I know everyone has their own interpretation but to me "Original" is the way it came directly from the manufaturer. Taking something and making it look like it originally did with the correct parts and paint is "Restored". From that point on, anything that wasn't original to the product is a customization.
I'll go one step further and add that in my opinion if you buy a complete original bike and add a horn or different handlebars it is customized. Even a bike that you bought with dealer add on accessories is no longer original,it's customized. In short, something changes from the original manufacturers intentions then it's a custom piece.