When restriction is removed the boost will raise , then the boost sensor will pick it up , and the computer will make adjustment to reduce the boost. however every engine may have different VE and if the boost adjustment is over the factory parameter it will light up the engine light. and yes you can tune after all the hardware goes on as well that is for custom tune . most of the flash tuning device are using preset parament for most of the car therefore. you can remove lots of limiter before putting the intercooler kit in too .