“Kona Dub-Rock.” That’s how Pepper describes their blend of reggae, alternative rock, dub, island rhythms, and punk rock energy. It’s a sound that’s taken the trio from the Big Island of Hawaii — where vocalist/guitarist Kaleo Wassman, vocalist/bassist Bret Bollinger, and drummer Yesod Williams held their first band practice as teenagers in the late 1990s — to the upper reaches of Billboard’s Reggae Albums chart.