I have FiTech. It is working really well for me, but I have read in various places that there are better systems out there, Holley being one of them.
I went down a rabbit hole for quite a while because the system would freeze and throw an "electrical interference" code. As luck would have it, lots of folks were battling the same code and solving it with various electrical fixes. After doing all of them with no luck, I alerted a friend who happens to own a tow truck, topped off the tank, and took off for a drive. I was hoping the system would "learn" and fix itself. 100 miles of normal running at 170+ degrees is supposed to be the magic elixir for the FiTech system. Desperate move for sure but I had read everything, tried everything, and wore out the tech service hotline. The self learning feature was all that was left before going back to a carburetor.
Topping off the tank fixed it! My "electrical interference" issue was actually low fuel pressure caused when fuel sloshed around and moved away from the pickup point. Before, I was just test driving a mile or two at a time, so no need to fuel up. The car ran flawlessly until it got low an fuel and shut down again.
A new tank was already on the to-do list, so I decided to scrap the external in-line pump setup at the same time.
After reading that, you are all probably thinking I am a colossal idiot. Well, you're not wrong! I console myself by claiming that it is possible that I had 2 issues at the same time. Phasing the distributor, replacing plugs and wires, triple checking the timing, running redundant ground wires, etc. was all good stuff to do to an old car with new FI. They just didn't fix fuel issue. That was separate.