Serious question about DET....

I am running in first/second gear around 2bar boost and in third a peak of 2.4 tailing to 1.9 bar and in 4th/5th 1.7bar flat........now i am using det cans but i aint sure of what the noise is really...i cant seem to hear anything unusual......right now i running a Collins ignition curve which seem quite advanded compared to the original base map....now with 7.9-1 and plenty of advance why will it det???thru heat??????..So if i make it run say 11.2 afr very rich will that cool it down enuuf not to det thru heat and where would the det really occur in 4th 5th gear only????