DVD Shrink - what compression has best quality vs. size(mb)?

[Naruto]

I got a dvd burner and used dvd shrink. My question is how high a compression can I go before I do notice some quality defects and it starts to stray from dvd quality? I do like to keep menus and possibly extras, but not too much at the cost of the main movie quality.

 

[waylman]

70% or higher is what I always strive for.