Fellars I have been a cng user for 15 years,At automotive components to install a new kit can cost up to ten thousand dollars,now it can vary depending on the type of car you own,now I am no expert so i am just telling you guys about how cng works for me,and what little i have heard .Firstly cng is safer than gas,when it comes to an accident because of the fact that the tank is thick enough to withstand a bullet,and yes the thank is heavy,depending on the size of thank you use,there are thanks of different sizes,eg.... it starts at 36liters53 56 65 70 and goes up to 100 liters as far as I know .Now about the weight the tanks can be as heavy as 150 lbs for the big thank filled,empty might be about ten pounds lighter [this is not fact just average] this is for the steel tanks.Now there are fibreglass tanks which are very light and strong also because they are combined with a special type of lightweight metal ,these vary in sizes also,and they are much more expensive. The disadvantage of these thanks is that the expire faster than the steel tanks, average lifespan 10 to 15 years.Yes you loose some power but under normal driving conditions you wont have a clue that the vehicle is working on cng.The other thing, people who donot understand cng simply badtalk it.If you dont know about it then it cant be good.Remember when fuelinjection cars now came into this country?.Now very few people want a carb vehicle.Now i really dont care for much trunk space so i installed two tanks in my car ,a 101 corolla ,its a 70 and a 36 litre,since a 100 litre will be two big for my trunk.I live in san juan and these two tanks take about on average 23 to 26 dollars to fill depending on the amount of pressure at the gas station pump. With this gas i leave home go to manzan,through rio,and come through princess town down the highway and back home with ac and then will have to refill.That people is almost 289kilos,for that price,steal of a deal for me.Now if you speed your gas milage drops,to around 235kilos.Iam talking of speeds above 110kms.Without ac I can get almost 310 kms. My engine is a 4afe so its just under 1600 hp and i have extractors.About the restriction of air ,yes you have to do it to get the correct air to gas mixture.And guys there is an air flow restrictor that opens when you flick to gas it reopens the airway to get yournormal air flow.And close when you switch to cng.Its like a butterflyshaft in your air intake hose,to bad for the inventors,hahahh,but it was a good idea,.Now i have heard that cng can be used on turbo charged cars but you have to buy special unit to manipulate the operation,i just cant remember the name of the part now.Oh and bythe way i have a pickup with a vvl engine and i run cng,under normal driving i run as fast as some small engine cars that run on gas.Whenever they give me trouble i flick to gas and go my way.So i wil advise to go with cng if you want to save money, if you on speed dont waste your time.Oh, and yes cng does work better on stick shift vehicles,simply because you can run your gears longer. IF ther are any errors ,excuse me since i had a very hard day at work and i am very tired.Hope this helps.One more thing the guy whose car blewup at chag main rd,the idiot welded two half tanks together,these thanks are moulded.