*zlibCompressionLevel* - integer value from -1 - 9. This configuration option only applies to the zlib compressor. When zlib is not one of the compressors enumerated by the `compressors` configuration option then providing this option has no meaning.

-1 == Default Compression (usually 6)
 0 == No compression
 1 == Best Speed
 9 == Best Compression

Note that this value only applies to the client side compression level, not the response.