i noticed a air regulator hooked up to the base on the turbo and mounted by the map sesor on his 99 250.what is the need and the purpuse of it.i dont have 1 on my 01.is this like a cheap version of a blowoff valve.and do you need one?

 

It is an OCR, overboost code regulator. The trucks computer will back the fuel off if boost gets too high, kinda along the same idea as a rev limiter. The OCR will stop the computer from seeing full boost and start to defuel if you boost too high. Riffraff makes the OCR and other companies make one but name it differently.