AppleQueso: Uh, I was never actually worried about the thickness. I just wanted to match a similar type of paper, as printing images on different types of paper affects the overall look of it, especially the brightness. And I found a paper that was a kind of a cross between normal and glossy paper (semi-gloss I guess), and it worked well. I printed off the new cover today.
Shoothimnow: No need to be harsh dude. Also, I didn't ruin the retail cover of my game. I bought the game, which was supposed to be in like new condition, but clearly the seller lied.