havent done a wj but a golden eagle yes.I was happy with the results of it(in stock form) had it rebuilt,impeller detailed,bowl work and added a diverter before i sold it,Definitely noticeable difference from before.
The wj is a mixed flow High pressure) so it might be cheaper to have someone do some mods to it instead The golden eagle/yj Is a axial flow(low pressure high volume)which will result in bigger improvements