1990 Isuzu Trooper Conversion kit?

So i have a 1990 Isuzu Trooper 4-Door and I was wondering if anyone knew what brand I could use to convert carburetor engine to a Fuel Injected one. I would like one that is not expensive, but will increase my MPG by a fair amount. If you can, give me an estimate of the expected mpg after conversion. (I get 14city and 17highway)