Yes, there's pro's and con's.
I've been curious about the FAST EZ EFI system and am glad to hear it performs pretty much as advertised.
I have also read a lot about the Mass Flo system and like it because it's essentially a mass air system which is, like he says, adaptable within a fair range of engine mods without complex tuning. And note that it uses off-the-shelf oem sensors and other hardware, even
the mass air sensor and tps are pretty much stock oem items, so parts availability worries are minimal.
I've got experience with mass air systems on my Lincoln daily driver, and there's little doubt they're the least complicated for the user and most adaptable. I'm using what started life as a stock 5.0 Mustang setup and ecu and just by going to a larger mass air meter and matching larger injectors it runs absolutely great on a 5.8 with decent sized cam, Edelbrock heads, much freer flowing intake and exhaust. In fact it's the same system other than the meter and injectors that ran just as good on the stock 5.0 motor.
Another one that doesn't get any ink any more is the Holley Pro Jection units. I bought one years ago when they first came out
and was absolutely amazed at the increase in throttle response and gas mileage over a 4bbl. In fact, I've still got the setup and am likely to put it on my 81 when I do the HCI thing to it. Now Holley has a closed loop kit that keeps the steady throttle cruising air fuel correct, and I'm going to use my Innovate wide band & meter to help tune the open loop. As far as tuning, they have a little control box with 4 adjustment knobs that you can adjust on the fly, it mounts inside the vehicle. With a wide band meter, that would be easily done for idle, accelerator pump, and WOT. And the new ones are around $1,000, kind of 1/2 way up to the cost of the FAST or Mass Flo systems, altho there's no doubt they'd be less fiddling with and pretty much a "plus n play" setup.
