I had a Stilo before the Mjet which i had converted to run on gas, but that was a 1.6 petrol engine.
I did actually ask if they do dervs, and they said they really only do company vehicles, such as vans, as it shortens the life of the engine, can't really remember why, though i think it they might have said it was something to do with higher pressures in engine, that was about 4 years ago though.
Have you looked in to it all beany or are you just thinking
I thought about it for the 1.2 but at £1200 for a professional to install it it would have taken me something like 12 years to recoup the investment
Car kits have to be installed by a certified installer or you could find your isurance going up, they don't seem to like amateur jobs for some reason (dunno why is only compressed flammable gas lol).
Your mpg will go down but as gas is cheaper you still save overall.
I seem to have something in the dark corners of my mind about having a separate oil feed tank, something to do with valve seals.
First task is to do the math really and see if it will be worthwhile, only trouble with that is we have no idea what petrol prices are gonna do in the next years.