I have used the KS3 spring in ALL the V-Twins. It saves belts, by reducing slippage. I have run it in : 02 P-650/04 V-Force/04 P-700. If you trail ride, run big tires, you want it.
There is ONLY ONE E.P.I. "black spring", it is # KSS3. See:
www.erlandsonperformance.com

 

Call EPI. They have great support. I bought my buddy springs for Christmas and called. They explained it very well