For my winter beater its 13.9:1 lbs. per horsepower. (2500lbs./180hp)
For my STE its about 12.1 lbs. per horsepower. (3400lbs/280hp)
For the SSEi its about 13.1lbs. per horsepower. (3800lbs/290hp)
For the GTP its about 9.1lbs. per horsepower, should be about 8.4 or so within the next month. (3650lbs/400hp...~435hp within the next month)
These are all rough calculations that I made from my guess of approx weight and horsepower.