That wouldn't explain their being no problems at full boost though it's worth a shot. I have an ebay adjustable with gauge that I could put in place of the stocker but I kind of trusted the stocker more. It seems there is a provision to hook the gauge up to the back of the Agency power Distribution block but I just don't wan't *more* fuel lines under my hood.
Also, just to let everyone know, I realized the MAF on my 05WRX was the exact same part as the 04STi so I swapped them to the same end result, e.g. cleaning it was enough, and it's reading fine.