There have been people at tracks with good road cars when the new 500 has been being tested and they said that the car just pulls away like they are standing still. Weight don't matter as much once its rolling. It matters most when the car is leaving from low speeds. Hence the reason they take boost and fuel away from cars and restrict hp versus adding weight.
In drag racing trying to launch a car and make it go as quick as possible in a short distance weight is everything. But then again you can take a Twin turbo car with 4000whp at 3200lbs and run it against a 3000hp Nos car at 2500lbs and they can both run the same et. So the hp the gt500 makes does matter and they will probably be a solid 700whp. Then to think about it like that. The car is just 120whp more than the new Ford GT supercar and 800lbs more weight and it will run a quicker et in the 1/4 mile. It also has the fastest 0-100-0 time out of any Ford ever produced. When the numbers come out of what the gt500 will do at the road track i think it will be like a huge WOW factor! It's gonna be a hell of car for the money.
Funny this comes up. I was at our local go kart track two years ago and a local guy there was 240lb and running laps with my 135lb employee whom was just a tad faster than me at 190lbs. All the same Karts.