:Design of experiments results indicate that PPE foam is feasible for use in headliner applications. These results correspond to the current use of thermoplastic foams as headliner substrates in Japan and Europe.Thermoplastic foams offer many benefits for headliner applications. However, one concern has been with heat resistance and environmental cycling, specifically heat sag performance. To address this concern, a Design of Experiments (DOE) was completed on Polyphenylene Ether foam to understand how PPE content, foam density, thickness, and thermoforming compression effect heat sag performance for headliner applications.The DOE determined that for heat sag performance: % PPE and density strongly effect heat sag Thickness does not effect heat sag Thermoforming compression interacts with PPE content in its effect on heat sag. This paper will focus on the methodology behind the study and indicate optimum foam configuration for heat sag performance in headliner applications.