PYPES GM X-Pipes make power! Because V8's fire unevenly, exhaust exits in pulses rather than a steady flow. While one pipe is filled with pressure the other pipe is relatively pressureless but the connecting of the two pipes in a siamese pattern allows pressure to be released to the other side. This action allows the exhaust to pass through the pipe quicker and increases horsepower. There's no skimping on materials here. All crossovers include dual 409 stainless reinforcement plates at the welds where they are needed most. All pipes are are mandrel bent, to allow for the maximum flow of exhaust gasses, which boosts acceleration. Fabricated using the highest quality materials, smooth, seam-coated, mandrel-bent, 409 Stainless Steel pipe resists corrosion and extends the life of your system.