If you are referring to Electronic Fuel Injection for cars/trucks, I have done extensive research on EFI. I'm planning, this coming spring, to convert my 1954
Chevy pickup truck street rod over to EFI. The system I'm sold on is made by FiTech EFI. They have several systems to select from based upon horse power requirements. I'm going with the 400HP unit. Their prices are extremely competitive and easiest to install and configure.
There are others aftermarket EFI unit, by Holley, MDS,....