On a turbo you use the power valve as a secondary fuel enrichment for boost,that is the reason for the 2.5 power valve.
As I have said before with a turbo you set the max fuel first then tune for driveability, after you know the total fuel demand for your HP. I have never had a carb back fire other than at full boost, you have many other issues to fix first.
Ask anyone about the location of the regulator, there are many reasons to place it as close to the carb and NO reason other than $ not to do it.
