Which version allows adjustments of the voladj settings?

All of the recent Hijack releases in the last few months or so. It's a config.ini setting, or you can send it HTTP commands to change individual parameters. It's all in the Hijack FAQ.

The current set of Voladj defaults in Hijack are actually different than Richard's original ones. They're ones that I came up with after these parameter-adjustment features were added to Hijack and then I created a little HTML form to mess with it. The form would throw settings at Hijack and let me test out the different levels interactively in realtime. There was a whole thread on it.