I finally found a good way to get good audio CDs from MP3s (in case you need perfect gapless playback even when your MP3s aren't gapless), this is what I do:

I open every MP3 with Foobar2000 being sure that in Preferences - Diskwriter - Processing, the options "use DSP" and "don't reset DSP between files" are enabled.
In DSP manager "gap killer" must be active and the maximum gap lenght must be of 53 ms (2304 samples are the maximum gap that MP3s can have, that means something more than 52 ms, so 53 ms is fine), smooth cut position must be enabled.
Now you convert every MP3 in WAV (using foobar2000) and burn WAV files with Feurio without pauses between tracks and the cd should be fine...

This is useful when you've got MP3 without informations about the right lenght (lame tag) and it's also faster than analize the lenght of every MP3 to see if the number of samples is a multiple of 588 and eventually scale down more than once if the gap remains...