if i want EMGs and i dont have a cavity in my guitar to put them in, is there any way i can have the batterys on the out side or the back side of my guitar??? because i really do not want to cut a big a ss hole in my guitar
You are better off routing a hole or having someone rout one for you. Then you can just put the battery inside. Most likely you could fit the battery somewhere in the potentiometer cavity.
If your talking about room for the battery, it should fit in your control cavity without routing. You could get it routed by a pro if you want, but it would probably cost a lot.
It should fit inside the electronics compartment in your guitar. But if you still want it to be "outside", its do-able, you just need to extend the wires and put a battery holder on the outside. Not recommendable for heavy users coz if those battery are knocked off and drop, then it'd be a different sound coming out from your amp.