I have an L-500L in my bridge and L-500R in the neck, I'm not sure if either are shielded. What are the differences in performance between the two? I imagine a shielded pickup would be better offering less noise ya? If so, why is there an unshielded option??? Educate me please. ALSO If you use L-500s in your guitars; what models do you use? L-500 R & L, C & L (neck and bridge)? I never saw the Cs until now. Thanks!