using phar and compression

Hello, i do some tests with phar. I have following script which is just adding some file and index.php is echoing "hello"; <?php $phar = new Phar('project.phar', 0, 'project.phar'); $phar->buildFromDirectory(dirname(__FILE__) . '/web'); $phar->setStub($phar->createDefaultStub('index.php')); $compressed = $phar->convertToExecutable(Phar::PHAR,Phar::GZ, '.phar.tgz'); ?> This is working and i can call resulting by: "php project.phar" Now i change last line to: $compressed = $phar->convertToExecutable(Phar::TAR,Phar::GZ, '.phar.tgz'); Now the final phar archive should be compressed with tar. Creating the archive works without errors, but i cant run it. Viewing file project.phar.tgz shows only binary-content, no php-header. Running "php project.phar.tgz" shows no output. As i understood i can run any phar archive, regardless of used compressionmethod. Is this right? Am i using phar the correct way? Thanks, Hajo