Both units are huge improvements over the stock single-pass heat exhanger. Here's a photo from the original install of the dual-pass Afco. Although obviously taller and thicker than the stocker, it's tough to show just how much taller and thicker. As mentioned before, the Afco measures 9 inches tall, 22.44 inches wide, and 2 inches thick, while the stock heat exchanger is only 6x23x1.25 inches. Even the standard Afco dwarfs the front-face area of the stock unit 202 to 138 square inches. So you can see why stock GT500s heat-soak so quickly.