In this talk, AvCarb will highlight key advancements in the design and manufacturing of Gas Diffusion Layers for high performance fuel cells. We will specifically focus on the improvement of mechanical properties of the GDL substrate and how this can impact critical factors such cell intrusion, pressure drop, creep, and compression set. Additionally, we will consider advancements in the construction and application of the microporous layer and how these changes affect surface roughness and more specifically surface roughness under compression, which is require the ensure compatibility with thin (<12 mm) membranes.