Not even 265 horse power is enough to violate the laws of physics. Newton's laws of motion effect the Xterra just like they do the planets.
An object at rest (stopped) tends to remain at rest unless acted upon by an outside source (265 horse). An object in motion (moving) tends to remain in motion unless acted upon by an outside source (brakes/fiction).
Mass times accelleration equals velocity. The more massive something is the harder it is to move. The more massive a moving object is the harder it is to stop. The suspension is going ot behave differently loaded up with sevral hundred pounds of PA equipment than it did when empty.
If you have custom shocks or spings made for you one of the questions they ask is your typical loading and if you want the suspension "tuned" for that load or for empty.
I've been an avid camper and outdoorsmen for +25 years. I do notice the differnce when the X is loaded with all my camping gear, extra fuel and water but much less so than my old 120 horse power Honda CR-V that the X replaced.