Hi there GH! Long time no post here.....
you might like to check out some LPG turbo installations at:
http://www.arunautogas.co.uk/autogas_lpg_conversion.htm
there are also quite a few turbo installations at Gas Research Australia.....
if you'd care to google them.
Actually, turbo or supercharging increases the volumetric efficiency of LPG and works quite well. I am toying with the idea of supercharging my old MB200 which is already running a venturi mixer. The supercharger will work very well in "suck-through" mode using a conventional carburetor and mixer.
just some thoughts too......
cheers,
steve