I don't see it like that. I mean you could have a really heavy car with MASSIVE RWHP but still be slower than a lightweight car with far less RWHP.
Power to weight and torque to weight ratio's are usually a more accurate guide. As only gearing, aerodynamics and power delivery willthen affect the cars ability.
The 05 GT weighs in at about 1650kg and has 300bhp/320lb ft
181.8bhp/ton
193.9lb ft/ton
As a rule of thub 200bhp/ton is where many people consider 'high performance cars' to start at. As you can see the 05 GT is not far off, especially with its very generous amount of torque.
Statistically its about right too
0-60 circa 5.5 seconds (maybe a little quicker with a good hook up)
0-100 circa 13.5 seconds
Top speed circa 150mph
All respectable times although not in supercar league.
To show as a comparsion the TVR T350 only has 350bhp/290lb ft from a 3.6 n/a straight 6
So a bit more HP than the GT but less torque. RWHP numbers would be fairly similar with the advantage going to the TVR but only by 50bhp MAX.
But the TVR only wieghs 1060kg (2337lb) giving it 330.2bhp/ton
273.4lb ft/ton
Giving it 148.4bhp advantage in real terms.
It shows upp in the stats too: 0-60 4.4 seconds
0-100 9.5 seconds
Tops speed 175mph+
A car like this will keep any stock 03 Cobra honest and even given some of the mod'd ones a run for their money.
So the key to making the 05 faster is to improve its power to weight ratio, which can be done by two means.
1. Increase bhp
2. Loose weight
The 05 GT has a great chassis and suspension that works with a bit of sensible buying and a few $$$'s there's no reason it can't shake it with the best of the best.
As my user name suggests, any car with 300bhp/ton or more is a serious performance machine.
And it is my goal and personal aim to have a car with such power. If its the 05 GT I buy then my target bhp will need to be 495bhp at the engine or about 440-450rwhp. So with the aid of a blower its cetainly a possibility.