Removing the Cummins ISX engine's emissions controls commonly called an "ISX delete" is the increasingly popular modification for heavy-duty trucks, although it’s critical to understand any implications. https://docs.google.com/document/d/e/2PACX-1vQaLgr02kMlzP6QS80UEc6sr00fBV1w9dphXYRESsHlcVRL5jXd8viaJgSFzLM72wHQkegQURxNZKX0/pub