As I said, it's subjective and could be more a case of not as much gain as higher up so it feels slower, but there is definatly a lack of go at 3k RPM. Driving along, squeeze it for a bit more, the revs go up and it pulls a little even on 3/4 throttle. After the revs build higher or it kicks down it flies.
I think the stages are an arbitary number each person makes up, there isn't a hard definition.
I've got an uprated pump and an FSE with stock 440 injectors. It's recomended I keep the boost down to 16psi with that setup. My intercooler has also seen better days which won't be helping.
Depends how wild you want to go.
I got them as at the time they were just a little more than stock replacments after blowing mine.