Turbo spool

I got an sr20det engine in a b14 sunny 4wd . Have a link ecu on it. Already tuned the car but seem to lack power before going into boost as turbo spool a bit late. Is it possible to make the turbo spool earlier by using a richer AFR just before like 3500 rpm?

Most unlikely, but it may be feasable to fit a smaller hot-side to the turbo' which should bring it in earlier at the possible (but not always) cost of top end power.

What is it currently fitted with, how much boost are you using, and any other pertinent information?

Oh, do you have the timing correct for it off-boost and at lower rpm - that can make a noticeable difference?