Again,
If you have backed up a GCN disc try compressing using winzip and it will compress to about 2MB if its a dummy!
HAVE YOU TRIED DDUMP?
If you have a good DVD drive (that can read sub data) its supposed to read around 40% disc surface... maybe even more if you use the surface scan...
download from -
http://www.geocities.com/ddumpfrontend/
if you have any luck make sure you use a hex editor to check its data and not dummy files!
Also use all ripping mothods available on the software!
other riping ways is the DC method with the cable from the GCN!
I think the main problem is playing them!
If we could by pass the barcode we wouldnt realy have much problem - despite rumors of disc spining backwards and data writen backwards bull shit!