Buy two sets of springs. You will need one for each carb. Additionally, you should buy two new vacuum diaphragms as they are often damaged due to frequent installation and removal of springs. I was told a long time ago to adjust the springs so that you don't have a noticeable "zoo-whaaaaa" when kicking in the secondaries in high gear at 45-55mph. If there is a noticeable bog, and then a pickup, the springs are too soft. All my experience is with a modified RB and six pack set up. I run brown or purple springs in my outboard carbs. If you are getting too big of a hit of fuel off the line, and that is leading to your bog, you can adjust the amount of accelerator pump hit by adjusting the nut on the lever that actuates the pump. Loosen the nut to eliminate some of the hit at launch.