How can I improve quality on my dvd?

I have been working with final cut pro for years, but now im struggling with bad quality when I exporting from FCP to dvd studio pro.
Im trying to make a dvd with 120 minute, but the quality is very poor. I know the quality can be much better since I made one with same length before using adobe premier. I have also tried burning the dvd with toast titanium but the result is still the same, so I think the problem is something with encoding or exporting. Can anyone help me?

Make sure your project is set to original/optimized media for playback. Export a master file in ProRes. Don't know what format you're working in, but probably that's as good as the media can get depending on what was done in the application. You can use Compressor to encode the video and burn a disc with whatever MPEG-2 settings suit your material and program length.