Instantcopy8 file size

i am making a backup of reign of fire and it seems that no matter what i do instantcopy8 always produces 3.45gb of files. this is almost a gig short of maximizing a dvdr. i even set the compress to something like 98% where the file was exepected to be 4.6gb. when its default is 92% for 4.35gb it still ends up 3.45gb. any ideas. is this a limitation of the demo. is it just crazy?

i had the same problem with the full version. i changed to anydvd and clonedvd with similar quality. all files come to 4.36gb. for high quality i use dvd2dvd-r with cce sp.