Just some additional info:
I had a 7th injector running off a pressure switch on the manifold set at .3 bar. As soon as the car boosted more than .3 bar the pressure switch would complete the circuit allowing the 7th injector to pulse at the same rate as the 6th injector. It was not ECU controlled. I removed this mod after the 3rd day as it mainly flooded the car and caused it to run poorly. I think it's not a bad idea, maybe if it was a smaller injector it would have worked better but I honestly think the detonation was caused by the timing. The knock sensor pushes back the timing but it can only do so up to a certain point and the lack of timing retard split that piston right in half!
Took off the head, looked at no. 6 piston still in the sleeve, couldn't see the problem, it looked perfect. I took the piston out of the sleeve and as I removed it, it split open like a banana. Right in half with a perfect line right through the middle!
So less boost, propper piggy back to run the 7th injector and you'll be fine. Ensure the knock sensor is functioning correctly!