Ah, ok. Weirdly, after driving around and checking it again, it actually moved itself and closed the gap slightly.
One thing I stupidly wasn't thinking about was that when I test fit the piece, I just assumed it would not scratch the paint. Boy, was I wrong. Ah well, live and learn. You won't see the scratches anyway behind the cover.
One trick I learned is to duct tape (I used black Gorilla Tape) the entire inside of the cover. That way, the fit is more snug, and you won't mess your paint up like I did.
I haven't secured it down with the 3m just yet (It's snug as a glove, I would trust it staying still without tape or anything) - i still have to enamel the edge I grinded down. Hopefully the fit will stay this way, it looks pretty damn sexy. EVO-R made a damn nice looking piece!
Thanks for the help guys.