We've discussed this before, and it was decided that in the States, what that number typically refers to is "pounds per horsepower", meaning you want a low number - but in Europe/Oceana, that number is typically considered "horsepower per kilogram" (or newtons, or whatever HP is measured in metrically), meaning that you want a high number.
EditAssuming that the PAL and NTSC versions are the same, you want low numbers, meaning each horsepower has to drag fewer kilograms. Most of the LM-style race cars seem to have a ratio number in the 1.5-to-2.5 range. A well-tuned street car will be in the 4s, and a less powerful or very heavy car may be in the 6-to-8 range.
Clear as mud? Add to that the fact that GT3 has totally screwed up the torque figures by displaying the decimal point in the wrong place (making them 1% of what they should be), and it gets confusing fast.