I tried this and it works mad!!! Love it. What i also did though was i used a change over relay, i put a on off switch on the dash when the switch is off the computer controls the boost and in the on position the solenoid gets gounded,
its the best possible way this mod can be done without any effects.
Change Over Relay Conections
85 - Earth
86 - switch on dash with 12+ volt
30 - to solenoid
87 - to the wire you cut going to computer
87a - Earth
Hope this helps
Chris