you don't need that at all. your 131 is fuel injected or carburetor setup?
you plan running on LPG or natural gas (CNG)?
in my part of the world LPG is 1/3 price of petrol and CNG (compressed natural gas) is 1/5 price of petrol. and it has nothing to do with new or old ways of extracting it, it has to do with oil cimpanies running your country!!!
Yeah the oil companies set the price on natural gas. I think our biggest issue with the price of natural gas is allot of chemical companies use it to make other products. LPG is mostly used for BBQ grills and furnances for home use in the US. Where a natural gas pipeline doesn't run in front of a house.
My friend in Serbia was surpised that nothing in my house runs on gas. Everything is electric. because it's cheaper to run a stove or furnance off electicity since coal and hydroelectric power is much cheaper.
I'd prefer to use LPG on a car simply because I think it would give a better range based on the size of the tank. I know natural gas produces more BTUs which means more power but LPG can be liquified at a lower presure than straight natural gas.