Is there any info about what impedance pickups should be used if I plan to change the stock magnetic pickups of my Korean JTV59? I just swapped mine out with a JB-SH4 in the bridge and Fender vintage single coil in the neck position. The single coil pickup sounded tinny and very low volume. There is obviously a mismatch of some kind. I am aware that this voids the warranty etc, but from reading the forums, seems like I am not the only one who is doing this. Some info would be appreciated.