The 05-09 Legacy GT ETS intercooler piping kit uses 2.5" OD 304 Stainless Steel tubing. This ensures the highest level of durability with our Extreme Turbo Systems kit The piping is 1 piece mandrel bent with no welds or joints to disrupt the flow. The ends of the pipes are beaded so you won't have to worry about couplers coming off during a pull. We finish our pipes in a wrinkle black powder coat. We guarantee the best possible fitment which will save you precious time during install.