When a spring is run closer to coil bind, it dampens the bouncing/surging when it is around peak lift because there is little room to move. If too much distance is available at peak, it can't dampen the surge. On an engine under 7500 RPM this is not as much an issue. It is even possible to have the spring set up correctly, but the harmonics of the spring is wrong for the RPM you are running. This is why I suggested a different brand. Edvanced engines Ed Wilson here is a dealer for PAC and can probably get you a fair price on them. Spend the money for an on the head spring tester to keep tabs on your springs, LSM or Pro Comp will do the job.