Maybe that was what he going to do next, but I never saw his buggy without the exhaust headers.
He probably still had them... Most likely he added a type of "turbocharger".
'Cause I remember him talking about an "exhaust gate valve".
http://auto.howstuffworks.com/question122.htmTurbocharger:
A turbocharger, on the other hand, gets its power from the exhaust stream. The exhaust runs through a turbine, which in turn spins the compressor.
(a waste-gate controls how much exhaust runs over the turbine blades.)
Now, I haven't looked to much into this part of stan's tech.
But , if you ask me, he's just using a "waste-gate" to control how much exhaust goes back into the intake. Thus "recycling" the "purified" water.
Thoughts?
By the way... I know that this doesn't really address the original topic... but it's a way to reuse the exhaust.