Sir its other way round. when driving on petrol which is around 106rs/l one has to be gentle with the gas pedal or it would hurt your pocket deep. When on cng you usually have to rev hard to accelerate though its no more chaper alternate to petrol.
As nomi bhai said, dohc is meant to be like this. You actually enjoy this car beyond 4k rpm;)
I never got the tappets adjusted. Just got throttle body serviced at 22k kms
Sir g you are more than welcome to try next time:)