Other than sanding/filing the CG where it makes contact with the case, not much. I have done this with some success, but you have to be pretty patient with Ti. Takes a long time to sand enough material off.
Also, be sure to use a VERY flat surface when sanding, or you will create gaps between the case and CG...
Take it slow and easy, and recheck it for fit often during the process. A little too much, and it will be too tight. Trust me on this one...