When every you change the gauge of strings on your guitar, you will have to make some acomadation to it. First the bridge , you would have to set the claw srews by taking off the trem plate the screws are in the trem cavity. Because your bridge will drop , when you put on the 8 gauge strings. Then check ur neck curvature. I. Know your probably saying whattt.
So take it to ur local music store if this doesn't make sence to you. You need to be careful, because you can make thinks worse. Hope this helps ya. Goodluck.