NOS Back Fire Issues. Any Ideas on amount of Retard????

Hi there have a 1987 Stang, converted to MAF, Installed a 200 Shot Wet kit NOS with MSD 6AL and 3 Stage Retard, Bigger Fuel Pump 255lph, Cold air Intake, 24lb injectors 76mm C&L MAF calibrated 24# & MSD Distributor.

When i was spraying 125 shot i was retarding 5 degress (at this point i did not know what base timing my distributor was set at) I had my mechanic set the distributor to 10 degress base timing and then steped up the NOS shot to 200. Well now i was only using 3 degress retard and all i get is allot of back fire and the Cold air Intake blows off all the time.

Any ideas of a proper retard setting would be great???????

Thanks MATT

I have mines hooked up on a Micro Switch that Activates at Wide Open Throttle.
I usually leave the line at 2500 RPM / 2800 RPM so after that its wide open and at that point its activated. Maybe the window switch is a good option for me and currently today i did 200 shot of NOS and 7 degrees retard and no backfire.

Whats Wrong with the Base timing? and yeah i understand about the 3000rpm point. I think I will ivest in a Window Switch.