Look at it this way, my home track would be Waterford Hills. The AS track record is 1:15.849 and the ITS record is 1:16.602. Less than 1 second difference. I understand the difference would be greater on a longer track but I can't imagine more tracks with more AS interest than Waterford. The ITS record is an RX7,BTW, not a BMW that will be moving to ITR. If a big braked, stiff caged Asedan with 375-425 horsepower is only 1 second faster than the top ITS cars, how will the same car with 100 less horsepower and more nose weight and stock brakes supposed to compete in a class above ITS?
In the mustang's favor, I would expect crank horsepower to near 300 or more in IT trim, tens of thousands of junkyard 17X8 wheels (light ones) and cheap crash repairs and maintenance. As far as the lack of upper rpm ability, I can literally build entire limited slip rear axle assemblies in the ratio of my choice for the same price as a ring and pinion or differential for most of the other cars on the list. I am still questioning the wording of the ITCS in regards to traction bars. These cars are utterly undrivable at that level without some sort of torque arm, 5 link etc. I would expect a 5 link is a no-go because you're replacing control arms and some of the torque arms incorporate subframe connectors. As far as the ones that don't , I would imagine they are a go. The flexy shock towers need to addressed. Since these cars already have a factory k-member brace that leaves tower to tower or fire wall to tower. Which do you think would have more benefit?
I agree with the SVO comments, I miss my 86 dearly. If there was a NASA track within 200 miles, I'd make one into an AI car in a minute.