Under the hood we found that the original air filter had gotten wet on the trip and practically got sucked into the engine. We added an Airaid intake and filter to try and get some better airflow, providing we stay out of the deep water. We didn't notice any added noise from the intake, and the installation was easier than spreading peanut butter on Wonder bread. It's hard to tell if the claimed 18hp gain arrived on such a big truck, but our seat-o-pants dyno did notice some change. We really like the 8.1L GM motor even if it takes our whole paycheck to fuel it.