These free-flowing, mandrel-bent Pypes X-Change X-pipes have reinforcing plates at critical locations and are available in 409 stainless steel or polished 304 stainless steel for years of high-powered performance. Since V8s fire unevenly, exhaust exits in pulses rather than in 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 more quickly and the improved 'breathing' increases horsepower. Pypes X-pipes' high-quality, exceptionally versatile design and performance are a proven winner when it comes to bumping up the horsepower of your daily driver or race car. On the road, Pypes X-Change X-pipes synchronize exhaust pulses, increase scavenging, and add up to 25 hp. At the track, they deliver an extra punch of power (up to 15 hp more) thanks to the built-in exhaust cutouts, which are strategically located after the exhaust crossover. There's no skimping on materials here. All crossovers include dual 409 stainless reinforcement plates at the welds, where they are needed the most. All pipes are mandrel-bent, allowing for the maximum flow of exhaust gasses, which boosts acceleration. Fabricated using the highest quality materials, the smooth, seam-coated, mandrel-bent, 409 stainless steel pipe resists corrosion and extends the life of your system. The kits include the X-pipe with extended legs, cutout covers, cover hardware, and installation hardware.