One point of interest is TTI's current 3" system will allow an H pipe with the GVOD.
Another point of interest is that the dyno isn't the only reason you make choices such as running an H or x pipe. Changes in sound, both tone and volume are also reasons to make the choice.
Last, dyno pulls often start at 2500-3500 RPM and chassis dyno's even higher depending on stall. Street cars typically live between idle and 3500RPM. Really all we have to go by in making these changes in regards to street performance is seat of the pants and our ears.