Has anyone got a 4.6is converted to LPG?

I have just had mine fitted with a BRC kit with twin Vapourisers. I also had a shallow battery fitted so I could get a 95ltr tank in.

I would like to know what mileage others are seeing from LPG

I pay 69.9p/l and have filled up twice, costing £50 and £52 which the later was 74.4 litres (i know they only fill about 80% because its gas). I managed 220 first tank and 250 miles second tank.

This was all motorway cruising 70 - 80. The computer had trouble getting past 19mpg - whereas on petrol i could get it to show nearly 24. (I was told to expect 2mpg loss on gas).

However if you do the maths it seems its only managed 15-16 mpg! I expected at least 300 miles from my large tank.

Can anyone else indicate what they get on LPG please? Not tried it round town yet, and its only done these 500 miles since conversion, has to go back at 1000 miles for check up but cant see that making much difference?

All help really appreciated - shelled out 2100 on this!!