I have no idea if it really works but I just spoke to a dealer the other day.
 He was running a special of $154.00 installed.  I asked him if he has put
any on an air-cooled Vanagon (since mine is an 82) and he said yes.  The
systems he was selling seemed well made.  He had one installed on his vehicle
and the installation looked clean.  If it does half of what it claims...wow!
Coop