File format or layout in GT

I have extracted a circuit file from GT3 A-Spec from the GT3.vol file.

Does anybody know which format these files are in or have any information on the file layout or decryption of it? I am pretty sure they are encrypted.

Thanks.
 
Wait. *Thinks*

GT3 files, I'm pretty sure, are both encrypted and compressed. As for decryption, I've got nothing.
 
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