I have been looking into the ms, terminator x, and a few others like fueltech and what not. I have ran Holley stuff on a previous ls build, but from my understanding even the kit for the 4.6 is built around the ls. The other few kits I have looked at outside of the ms kit and Holley kit is a little high for what I’m building “I am sticking to somewhat of a budget”.
As for the ms vs the Holley I don’t personally know because I have never messed with the megasquirt only read about it. I agree the factory gauges are trash for sure, but with that being said I am still on somewhat of a budget unfortunately. That is the main reason I have been leaning to the ms. From what I read it seems to be the easiest one to install and mess with.
I have built a few things where I had to make stuff work, build my own harness, build brackets, and just spent way too much time and money for what it was worth lol. This car I have tried to keep it as 2v 4.6 mustang gt as I can, but still handle a decent amount of hp. That is why I left it a 2v and didn’t go 4v or put a 5.0 in it. I just really didn’t want to mess with that on this car. I guess that’s why the Holley kit was kinda second to the ms but I will continue to research on what will do best for me.