What's the name of the song?

It's hard to describe, but te hear it sometimes when a character (mostly Luffy) does something good. For example, when Luffy found an "Atlas beetle", o when Luffy was shown to be immune to Enels lightning powers, o when Luffy fought Alvida's crew, ect.
I really want to download it, but I got no trackname. Please help & thanks to whoever does.