I did the EFI with coils about 10 years ago with a AEM ecm and LS coils . It is nice to be able to tune fuel and timeing on a individual cylinder. I run 400 hp nitrous .
But with out EGTs or 8 O2s I am not sure I would bother as it is going to be a tunning nightmare .
I have 8 EGTs and 2 O2s .would like 8 O2s but that is cost prohibitive.
We are running the Factory Ls computers on some stuff and I can tell you it is good stuff . It how ever is not as good as A good aftermarket ECM . I have A lot more usable features in my AEM. the factory Ecm is dedicated where others make them much more flexable.
As you can see I covered my Ls coils as they are ugly as sh!t