Just to add on to Jack's posts, I also noticed a distinct upgrade to the power during passing. Also the quickness of the shifts on top of the extra hp makes me hate going back to stock!
I have an 05 XLT with the 5.4 just for reference.
Also the 89 octane, if the engine isn't tuned for it, really can't provide more oomph. It also won't help in gas mileage for the same reasons as power.
How it works is that the octane makes it burn slower under the same pressure, or burn at the same rate under higher pressure. This is an advantage in high compression motors, such as your motorcycle, or most racing engines, but in our trucks it isnt necessary, and they can't take advantage of it without tuning. With some octanes, I dont think 89 is far enough off of what our trucks are designed for, it can actually hurt gas mileage and power because it burns too slow. this could possibly leave unburned gas in the cylinder which would then exit out the exhaust and possibly causing backfires or in racing motors that cool blue fire
.
Hope I helped you and everyone understand more
, and if I am wrong, feel free to correct me!