From what I know, the "power" mode on the trans only makes downshifts faster & holds out the gears longer before changing. In econ mode, there is probably little gain as the trans will be changing before say... 3000rpm. At 3000rpm and higher seems to be where all of the I6's develop maximum torque.
+ Go the 2.5" exhaust. Either cat back or with extractors. With extractors it does develop better lower end torque, and if you add cold air aswell, overall torque on the engine improves aswell.
What about suspension, or doing springs first so it rides better?
Hope the above information is correct!
Best of luck rabbi
EF Fairmont Ghia. Luna Mist. Tint, Factory lowered, 16x8, 16x9 Milanos.