Update:
I was driving my car and it instantly shut down. Phoned the mechanic who came across and started looking at electrical components. Apparently the relay controlling the alarm system had worn out and had to be replaced.
Anyway, i have no idea what happened, but as the guy was ruffling through the harness, something may have clicked, something may have grounded - not sure but something happened. So the car starts back and then the Greddy MSS shuts off. Apparently the jack was slack and become dislodged. So we simply plugged it back in.
The popcorn/back firing sound stopped. The car is running sweet...no noises when decelerating or anything.
What could have happened here ?
Is it the Greddy was keeping the car in "rich" mode thereby allowing extra fuel to be present for the back firing sound ???