Starting Line Products Exhaust Valve Springs - Yellow 14-113 Polaris exhaust valves open with cylinder pressure. As you go up in elevation, cylinder pressures are reduced causing exhaust valves to open later than they should or in some cases not at all. This can cause poor and inconsistent top end horsepower. Changing to lighter exhaust valve springs allows the exhaust valves to open at the proper time maintaining proper top end horsepower and running consistency. Order 2 per engine