umm i think this is what they were on about on the sxoc
SXOC Bulletin Board
this only a link to it being for sale but im sure if u PM'ed the guy he'd be happy to tell u his experience with LPG.
I feel its a great idea for the time being maybe buy one already with the conversion already fitted, but im sure its gonna start catching up with petrol in the not too distant future and will stop seeing any advantages doing the conversion yourself