Francis,

I put those on my old bow and they made a little difference.
For $20, I would get the S-Coil first (or both).

BassPro has a Sims Kit, which seems good for the money and should
quiet the bow down some (but don't expect miracles):

http://www.basspro.com/webapp/wcs/stores/servlet/Product_10151_-1_10001_79284_400014017_400000000_400014000_400-14-17

Good luck.