Alright guys, I've just recently changed my strings on my SG to Ernie Ball Not Even Slinky's (12-56) and I've noticed that the g string kinda sounds muted. As in it's not ringing fully or something. I've did some thinking and I figured that it could be the saddle or possibly the nut. Which one do you all think it is? And if it is the nut should I buy a nut with wider slots or something? Or if it's the saddles that it's fixable by me?

Thanks, Daniel
If the nut slot is not wide enough for the string then you could have someone just file it out to the right size. I always do that myself because I use thick strings as well. That is also the easier of the two but it's irreversible. So don't get too crazy with it. They have small cylinder files perfect for this. The saddle, Im sure you could take care of yourself if your mechanically inclined at all. Im not saying either will for sure fix the issue. But it's a good place to start.