Check out the first few posts in every section, the ones that have a "pin" icon to the left of them. Those are stickies which usually contain commonly asked questions. In this section, there is one about first mods to a car.
If you can't find what you are looking for in the stickies, hit that search button. This is a topic that is covered a lot, so instead of creating a new topic, let's post in an existing one please.