My car has a custom exhaust system that pretty much approximates the European car's exhaust system, seems to add around 25 hp or so (american 3.8 and 5.0 cars have incredibly restrictive monolithic cat-cons). I guess torque is relative, but my car can easily pull up a steep back-road hill at 2,000 in 3rd without having to hit second for a higher position on the torque curve.
Btw, my car's stock peak torque was 195 hp @ 2750 rpms. I imagine that it makes its peak torque at a lower rpm than the I-6, thus, it has a torquey "feel" to it.
And doesn't your euro W126 have different cams than the US version? That would make sense, too.