when i had my gtr motor rebuilt the only extra (performance) work done was a bit of porting, port matched manifolds and a set of 264/272 cams, can't remember the lift but only a little above stock.
i found that full boost came on a little earlier (maybe 200rpm) made 40kw more at the wheels and the responce on and off throttle was better. this was with -5's. curious if i could have had a better cam choice.
as far as off boost responce, well i was making positive pressure by 2000-2200 and 8psi by 3, from there it came on a bit slower but very linear.