I recently bought a Squier Telecaster Custom HH, and I get this god-awful feedback when I engage my wah pedal. I don't think it has anything to do with the amp-wah combo.
make sure your leads are in the right jacks?
i saw this earlier.. something about its plugged in backwards/wrong
I had another guitar before this which didnt show these tendencies.
should some rewiring be done?
Im pretty sure you have the input/output switched on the wah.
sounds like you got your wah output mixed up with your input. swap the plugs around.
I honestly don't think its anything to do with the input/output being mixed up. I had borrowed a friend's Epiphone LP earlier and there were no hassles with that one.