Catalytic converter mechanical robustness depends on maintaining a certain range of mat pressure to firmly hold the honeycomb ceramic substrate from moving inside a catalytic converter during its service life while avoiding fracturing it in the manufacturing process. Durability, robustness and performance of the converter assembly need to be predicted for designing the mounting system parameters.This paper investigates the major factors that affect the mat holding force. An innovative substrate hot push-out test method is presented to measure the mat holding force, providing the key performance data earlier in the design cycle. DOE data along with statistical analyses are presented showing the correlation between the mat holding force and various key factors.Hot push-out test can be used to replace the current key-life testing method as a cost effective pre-screen test method that enables robust design earlier in the design cycle. It can also be used as a prediction of catalytic converter's durability performance.