Working with the file config.php is performed by connecting the "Site settings" (the file includes/config.php, class Config).
void save (array $new_values, array $languages, [string $save_demo = false]) – Сохраняет параметры сайта.
Example:
Custom::inc('includes/config.php');
// enable "Development mode"
$new_values = array('MOD_DEVELOPER' => true);
$languages = array(
array('id' => 1),
array('id' => 2)
);
Config::save($new_values, $languages);