For starters fix the MAF issue....If its a turbo car there should be no issue in locating the MAF in a good run of pipe. Secondly....how do you know its detonating? Because the over sensitive microphones on the side of the block are saying so?
Thirdly.....these cars never run in "MAF only"......you really should be fixing the Air Per Cylinder model (SD) or you will have all kinds of issues with this. Take a look at the VVE over 105 KPA.....