AFIK, the rods/pistons in the European 2.0 Duratec can handle the 220HP that two builders in the U.K. are doing with that motor. Above that, they swap out the rods/pistons and keep the crank (shorter stroke/no cast balance shaft drive gear) to 270HP where a forging (or billet; I forget) is used.
Our 2.3 may have different, even lower limits due to stroke, piston speed (rod small end) and rod material (sintered/powdered metal/cracked cap).
Peppy for me doesn't start until you hit about 275-300 whp.... But then again, I'm jaded!
With the 2.5L truck I'd look to get 300lb-ft of torque with a turbo unit if I could get enough flow into it. The rear end, gears and trans are suspect after that. Plus its a truck and relatively light weight with high rear end gears, so you really don't want super hp because you'll just nuke the tires.