Compress DVD movie and normalize audio or the opposite?

I have a DVD main movie (MPEG-2, 720x576, PAL 16:9 ; one audio stream Dolby digital, 48000Hz, 6ch) that I need to compress a bit (about 7-10%) so as to fit on a single DVD-5. Also, I found (on previous non compressed short movies) that normalizing the audio stream gave much better results on my DVD player and 2 speakers (if not normalizing, I must continually change the volume while movy is playing) . Now I wonder if I must first compress the movie (I use Nero Recode 2 or DVD Shrink 3.2.0.15 for that) and then normalize the resulting Dolby audio stream (I use TMPGEnc MPEG Editor 1.0.1.59) or the opposite. Usually normalizing to 90% is ok (any help in this field will also be greatly appreciated since I don’t understand what represents 90% and why it also increases the overall volume level).
Thanks for your advice

Hervé

it wouldn’t matter which order you do it in. transcoders (like dvd shrink or nero recode) don’t modify the audio streams you leave in.