Duramax Tuner is a leading manufacturer of drop-in turbos and testing/diagnostic equipment for Chevy Silverado and GMC Sierra diesel trucks. Upgrade the performance in your Duramax with a Stealth Mach 1 or Stealth Mach 2 turbo. These drop-in turbochargers offer a stock appearance with increased performance across a wide operating range due to upgrades such as a high flow vane (HFV) technology, oversized turbine wheel, and a billet compressor wheel.