I think.....please correct me if I'm wrong......that the GCC only works in conjunction with the F-Con or the VPC - the rotary controls adjust the fuel curve over the rev range.
A bit dated now compared to Apex Safc - but reliable and well proven when set up right.
One of the best DSM (4G63) drag racers in the states uses VPC/GCC combo for some stupendous horsepower.
Check out the web page at
The old project car ( Project Hugger ) uses this set-up. I have a good magazine article on this car too in a US edition of Turbo and Hi-Tech performance .