I was in a predicament earlier today where I was stuck with a downloaded (ripped) DVD which was slightly larger than the capacity of a single layer disc. Fortunately, the disc came with an optional Italian audio component, which, when removed, would allow me to burn the DVD without any issues. While I was aware of DVD rippers where you can specify the audio streams that you would like to retain, I was looking for a solution that would work on the VOB files directly.
DVDShrink is the answer to the above conundrum. While aware of its popularity among those who want to compress dual layer DVDs to fit onto a single layer disc, I was heartened to see that it also worked directly with VOB files. It was a cinch to uncheck the Italian audio component on the DVD in question and create a new ISO which was now well within the limits of a single-layer DVD's capacity.
Jubal is a happy chappy :) In case you're running Linux, while sourcing out this solution, I also read that DVDShrink works fine under Wine.