I know these systems aren't as smart/precise as bigger injectors etc.. But are these systems better than the usual adjustable FPR boost upgrades? These systems seem to be cheaper and somewhat tunable. More so than the fpr thing.

Yes, maybe not equally as good as larger injectors, but there are lots of benefits to running them. I looked into this. With emanage, you can run a 16x16 map just for the additional injectors, and what is even better is that you can base it off of MAP vs RPM, so when your MAF is maxed out - even larger injectors can't be controlled... but MAP based additional injectors.

Way better than FMU imo, but to do them properly you end up spending nearly as much as just upgrading to larger injectors the right way.

Thanks. I'd would be nice just to add 1-2 injectors and have it run some pre-mapped amounts of fuel (rpm or boost based) and let the stock ecu / injectors fine tune the system? I realize the atomization of putting two injectors somewhere near the TB is not the greatest but seems like less trouble than an all out injector swap.

Swapping injectors was cake.

I was shocked at how easy it was. The hardest part is letting the wd-40 soak on the injectors for ~20 min. before trying to remove them.

Additional injectors is the old school method for supplying extra fuel at WOT in a boosted car. It works pretty well, but it used to be difficult to provide a smooth transition from NA to partial boost to full boost. Corky Bell invented the boost-referenced fmu in an effort to make a smoother transition.

One concern with doing this is how the intake manifold is designed. It is much easier to design a dry IM than a wet IM that has to ensure even flow of gasoline droplets as well as air to all the cylinders. Using a dry IM as wet may result in lean cylinders. I haven't heard of any nitrous users having this problem, though.