Athena spring contrast variator - Green of the source: 25 KG A difficult counter-pressure spring causes a subsequent commutation of the converter, which interests in better satisfying the motor. When a sports exhaust, it can be helpful to use a harder contrast spring to get better acceleration. Lighter Vario weights and build in a harder spring back pressure together can have a negative effect. Please try individually! The different strengths of the spring are distinguished by the color. Athena indicates the differences in kilograms, which press against the transducer: - Blue: 22 KG Use: original spare part for slightly tuned engines - Yellow: 27 KG Use: slightly tuned engines up to 10 HP - Red: 32 kg Use: high-powered engines tuned over 10hp original replacement engines for some tuned: 25KG Usage: Green - - Black: 30kg Usage: 10hp slightly tuned motors - Purple: 35kg Usage: High tuned motors over 10hp