There's a 15+ page thread on
Mustang6G.com. To summarize:
1) Ford has not released any official specs for weight or power output.
2) There was an interview back in 2010 where a Ford engineer was hoping to shave close to 90kg from the outgoing S197, but that was back in 2010. Coupled with completely misleading rumors from the likes of publications such as [the now defunct] Edmund's Insideline that the S550 platform would be about 1.5ft shorter in length, the community has assumed that there would be a 200-300 pound reduction in curb weight. The S550 is actually very close dimensionally compared to the S197; lower, similar length, and wider in the rear.
3) IRS does NOT add 200-300 pounds, contrary to what a bunch of ignorant people tend to post. For some reason, there is frequent referencing of the '03 Cobra's switch from a solid rear axle to IRS as the reason why it weighed an extra few hundred pounds more than the vanilla GT. What people don't take into account is that it had beefed up running gear and things like a supercharger, which will add significant weight. The IRS in the 2015 is an integral link type, unlike the "control blade" suspension in the Cobra. It's also much more aluminum-intensive, and should realistically add no more than ~100 pounds from the outgoing SRA.
4) What
does need to be taken into consideration are the updated regulations that the S550 has to meet; particularly the safety standards for both US and EU markets. Structural reinforcement and the four additional airbags is not something that's easily overcome, despite heavy use of aluminum in the hood, front fenders, and (I think) trunk lid.
5) Steeda didn't give us specific weight figures, nor did they strap it to a dyno and give us WHP/TQ numbers, which should be as easy as 1-2-3 for them. Why be vague with something as important as this if they know the answer? If anything they have pre-production models. Not that weight should change significantly with a greenlit production model, but still.
6) Some have made good points coming up with ideas as to
why Steeda would do something like this, which would throw out any likely NDAs. Maybe they're anchoring the weight at something that's initially shocking, so that Ford can come out and announce a marginal weight gain. This way it makes a much softer blow and doesn't completely disappoint the large crowd that was expecting a weight loss.
7) There has been a clear statement from a Ford rep that the S550 GT with a PP outrunning a Boss 302. That could mean anything, but what we can infer is that such a weight gain like this rumor would make it extremely difficult to meet that initial claim. Food for thought.
8) The C7 is 100 pounds heavier but far better in (I think) every parameter compared to the C6. Chassis stiffness/rigidity and powertrain tech is extremely important nowadays. If weight has gone up, is it in the right areas? How about unsprung weight?
There's a lot to think about with these latest batch of rumors. We should just wait for Ford to release the full sheet of numbers, and, most importantly, wait for real world testing and eval.