A Fogger, is a way of very finely atomising a gas for injection.
They are typically used in Direct Port Nitrous systems as a way of injecting the Nitrous Oxide into the engine.
In theory they *may* be used for LPG...BUT and it is a very crucial safety point....the LPG 'mist' created could in effect be too volatile and could ignite inside the fogger or plenum chamber with nasty results.
The way Nitrous Oxide works, is it doesn't itself sustain combustion so can *safely* be finely misted, but when it is heated in the combustion chamber the Nitrous Oxide splits and increases the Oxygen concentration by a significant amount, and Oxygen burn very well so it increase the explosive power of the current fuel/air burn by introducing extra pure oxygen into the reaction.
A fogger with LPG *could* create a perfect storm combination of a very fuel rich vapour in a hot space with inducted air, and as we all know from GCSE Science, that a fuel vapour ignites at a much lower flash point temperature than a heavier fuel vapour density.
Also the LPG ring has been calibrated to introduce a measured quantity of gas over a given amount of time.....trying to matc hthis with a fogger could be difficult and dangerous....
Just my opinion...if you want to increase gas efficency, I would look elsewhere in the system, mixture, water jacket temperature on the Gas expansion valve etc....