This is interesting to me because I have been considering using a GM solenoid for some time now. The AEM ems uses gm solenoids because their one of the best. I was going to just replace the stock solenoid with a gm one and hook it into the Utec and use it that way. I am not understanding why the manual controller is needed? Is it solely for boost spike atmospheric changes? I now have a profec b spec2 and cant tell you how it works yet. Im braking in a new clutch and cant boost the car. I have been told over and over not to use the utec to controll boost on my 18G because the factory solenoid wont respond fast enough to regulate boost spike. So my first thought was to change to a gm solenoid. Like I said before is the manual unit necessary or just for spike situations? Im tossing this one around again now. Anyone want a Profec thats a week old????