granted you may not NEED to tune it because it will work without a tune, but if you want to squeeze every pony out in a SAFE manner you want a tune. Each car is tuned differently.........for example, my d16z6 with the same kit would be tuned differntly than someone elses........the tunes are both different, even thou the motors are the same.......

 

But the thing is Pete that part of what makes it CARB approved is the pre tuned FMU "box".