I understand the Mustang still handles much better then the Camaro even with a solid rear axle but im curious why not just put one in and make the Mustang dominate the Camaro even more. For the most part, GT Mustangs are generally not taken to the track and if they were, a 300-400 hp Mustang is surely not going to break the IRS. Just like when the Mustang made the jump from carburated to fuel injection I think it might be time to step up to IRS. Solid rear axle may be demanded on the drag strip, but for your average sports car enthusiast I think its more about the way it handles. By the way, look at a 03-04 Cobra with IRS vs Mach 1 with solid rear, the Cobra pulls close to .9 g's and the mach 1 is .84. Clearly the IRS makes a difference. Also the IRS on the Cobra supports the terminator motor which is stock with 405hp.

The last question I have is why does Ford continue to use the 5 speed transmission? Theres a reason why if you step up to a GT500 or a Cobra you get a 6 speed tranny, and thats because its superior. For one, you can obtain a higher top speed and even more importantly you can get better gas mileage. How you ask? Keeping the RPMs at a minimum helps to save gas and makes cruising a breeze. Theres a reason cars are getting more gears year by year.