I PURCHASED A 1986 CJ7 A FEW WEEKS AGO THAT HAD A DANA 44 REAR AXLE AND AN AFTER MARKET MOPAR EFI SYSTEM.  THE AXLES WILL GO DIRECTLY ONTO MY 1982 SCRAMBLER.  THE EFI THOUGH I DON’T KNOW.  I’VE READ EVERYTHING I CAN FIND ABOUT IT AND THERE IS NO DOUBT THAT PERFORMANCE IMPROVES.  HOWEVER, WHAT I WOULD LIKE TO KNOW IS WHAT HAPPENS TO THE GAS MILEAGE? BETTER? WORSE? SAME?  

I don't know about a Mopar EFI but with the Howell I got 2 to 5 mpg better fuel mileage and a lot more power. It makes it start good in cold weather too. If you are going to drive an old jeep much it is a good investment.