Compressed files in Stunt Racer 64 begin with the following header structure:

struct CompressedFileHeader
{
    /*0x00*/ u32 srcSize; // total source size
    /*0x04*/ u32 dstSize; // total destination size
};

After the header are contiguous zlib-compressed chunks, each preceded by a subheader containing the source size of the chunk:

struct CompressedChunkHeader
{
    /*0x00*/ u32 chunkSrcSize;
    /*0x04*/ u8  compressedData[]; // 78 DA ...
};

The file and chunk headers are aligned to 2 byte boundaries in ROM.