New upgraded Primary Spring that has 1\3  the tension of the factory primary spring
This spring is made from ASTM A228 Music Wire and is made in the USA
This spring will lower your RPMs aproxamatly 500 - 600 across the entire operating range reducing engine noise. 
There is very little reduction in Engine Braking with lighter primary spring. 
 Delrin washer included to keep the spring from binding during compression.