I had the EXACT same problem with my lip after I got it, same exact gaps and everything. Really pissed me off.

I finally played with it a bit, and got it to fit perfectly.

The reason you have those gaps where they are is that the lip is mounted too high, if you lower it a bit (here's where you play with it), it will close those gaps up nicely and will fit well. Another thing you may have to do is place the spacers on the very outside mounting positions, this should allow you to get the lip low enough where it fits. You will have a space between the ends of the lip in the back and the fender (next to the wheel inside), just make up some plastic or wood pieces to fit there, paint em and you'll never know it.

I wish there were instructions with these, but if you play with it, you will get it to fit perfectly.

Mine's still holding up well after many (very fast) miles, so don't worry about placing the spacers in the outside mounting position.