Are the engines for pre-2000 pathfinders and QX4's the same?

If so what upgrades can you do to give the engine more power than the 165-170 that it comes with?

I know they make a supercharger but thats a little rich for my blood right now...

TIA for any help.

The 1999 QX4 enginge is exactly the same 3.3 V6 in the pathfinder. Same torque and power. For a little more power you could put in an aftermarket air-intake filter, and a new exhaust system. Intake is anywhere from $50-$150, and exhaust runs from $250-up.