Would there be interest in a dodge TBI setup made for our cars?

I'm interested in the gas mileage improvements. Can anyone throw out some figures? Even if it is only 2 mpgs that's worth the $300-400 for this upgrade over the period of a couple months. Does EFI improve mileage a lot more than TBI or is it about the same? Just wondering about the details of this. Thanks for any info and good luck on making sales 66plyValiant!