Ok found it here.

https://www.mustang6g.com/forums/thr...-track.110246/

Well, the results of Car and Driver Lightning Lap 2018 are in, and it hasn't been kind to Ford.

Not only did the Corvette ZR1 demolish the three times more expensive Ford GT - 6 seconds faster at VIR, same day, same drivers....

https://www.mustang6g.com/forums/th...ternational-raceway.97684/page-7#post-2350669

... but....

The Mustang GT PP2 consistently overheated in as few as 3 laps, and continued to overhead even when cool down laps were thrown in between hot laps.

Here is the exact quote from Car and Driver:

"But with no differential cooler, the rear axle overheated every time we took the Mustang out, often in as few as three hot laps, and even with easy laps staggered between them."

So there you have, leaving out the coolers was, again, a major fail by Ford.

So now, what? Wait for Performance Pack 3?