yes tuning is crutial to the response of the car. When i turboed my 02 civic si, i had turbo lag between the time i installed it and the time i spent on the dyno. I normally would have full boost by 5200rpms before the tuning, and after i had full boost @ 3800. This was done using a Turbonetics T3/60-1 turbo. This thing was enormous for a *eco* vtec honda 4 cylinder.