[MKS427]

I have a FiTech. I made the change because the vacuum issues created by the big cam caused sputtering and bucking below 1800 rpm. I works great, but it is not self learning, you have to program it with the included handheld module. 400 hp system would be about $1000-1200 plus a 177 lph in tank fuel pump and a return fuel line is all you need. The computer and fuel pressure system are all inside the EFI.
Another consideration, is where to put the O2 sensor. If you have collectors in your headers, that is ideal vs tapping into the sidepipe. If the sensor is too far downstream, you may have issues.