The installation procedure calls for welding the bottom of the tubs to a flange, but due to car-to-car variation, it’s not feasible for DSE to make a one-size-fits-all piece. That means it’s up the installer to make a custom flange, which is much easier than it sounds. Start by tracing the outline of the floorpan onto a piece of poster board. Next, draw a second line an inch apart from the first line that follows the same contours. Cut along the lines to create a paper template.