Theres a road rally shop here in IL that custom builds the cars from scratch......4wd, 4cyl turbos pushing 300+hp. I spoke to these guys and one car they were working on had over 400hp....ran at 26psi of boost and idled at 3psi of boost....."theres no turbo lag in that one" he said laughing.....he also told me the car does wiked 4wd burnouts being so light with that much power!!!
Turbo lag can be compensated much easier then spending millions in RD to incorporate some electrical motor and adding more weight to a car.