Nice share bro. 7th gen civic needs a lot of care if on CNG. I personally have a manual Exi on cng, driven like 150k kms. It used to give me rpm drops, jerks, bad mileage etc.
But a genius electrician found the best solution to the problem, he earthed the CNG kit with a zero gauge wire directly from the battery! That day onwards, its been moving like a charm on CNG.
Regarding the mileage, it gives me excellent mileage for a 1500cc car.
quoting last sunday, it gave me 183kms in a 682Rs fill.
Drive was like 30kms intercity W/O ac, 75kms on highway with AC, max speed being 130kph, and the rest without AC on highway.
Conditions are fuel injectors clean, engine flushed, spark plugs in excellent condition, CNG adjustment done by a v.expert person, air filter clean. Thats pretty good regarding the size of the engine this car has.
VTi is supposed to give even better mileage than this, though never tried a D16w9 on gas.