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Holley hit the nail on the head when they named the mechanism for their vacuum secondary the “No Trouble” design. Compared to how you used to change the spring in the secondary, this is a snap. Mena opted to change the spring from “purple” to a stiffer “black” one. According to Holley, the secondary springs regulate the opening point and rate based on venturi air velocity. From heavy to light, these black, brown, plain, purple, yellow, short yellow, and white springs affect how the secondaries kick on. Holley recommends starting with the black spring and working your way down. When you can feel the secondary come in hard, go back to the previous spring until the acceleration feels smooth.