MBH E55 304 SS Longtube Headers Welded in house with extensive dyno testing on a Dyno Dynamics dyno. We were consistently making about 45 wheel horsepower over stock with just long tube headers as the only modification. Gains on our E55 AMG long tube headers went beyond the 50+ wheel horsepower mark when they were paired with other modifications just as tuning, throttle body, or pulley.