The turbo lag could be the turbo "choking up" with solidified oil junk, from not letting it cool down after driving hard. A good roller bearing turbo will fix this.

A healthy SR20DET will get you mid 12s in a 1200. Get:
a 3 inch mandrel exhaust
a 3 inch Cat convertor
A big intercooler (don't chop up the front to make it fit)
up the boost to 12psi

You can expect up to 230ps (270ps with roller bearing) at the wheels with this combination.