hairy_hen said:

Combined with the non-defeatable 4 db reduction in total volume that comes from the Dialnorm parameter in the AC3 stream, the result sounds very anemic, much less powerful than it should.

Non-defeatable? Why didn't you ask: http://www.coises.com/software/vobdnorm.htm

The only problems are that it's command-line, only works with VOB files, and you will need to do each VOB separately (it doesn't automatically move to the next file).

Still, it does just what it says on the tin: it lets you rewrite the dialog norm to any value without re-encoding.