well theres an experts answer above , was going to say if using igmburn try turning on and off the various options in advanced mode.
Can I ask what blanks and speed u burn at to get good results with dvdr 5 ?
also when I did a few test I burnt a few dual layers in safe mode and this did reduce the scores down but not by much , best bet would be to look at various setting people have got good results from burning xbox360 games and using them
you could try burning in safe mode to see if theres anything pulling down your burns I gues. at least it would eliminate things