Stock Diameter Performance 1.289 Beehive Valve Springs The unique design of the Inverted conical valve springs offer increased harmonic resistance for greater spring stability. This design requires less spring pressure for better valve control. Test have shown more horsepower, high rpm’s and longer life expectancy. This design is well known on GM Gen III (LS1/2/6) applications, but is also great for other applications including Chevrolet small blocks, Chrysler 5.7L Hemi, and many other performance applications.