Go outside, run to the top of the nearest tall hill, scream for a few minutes, come back, and then go at it again. That always seems to work for me when my programming code at work isn't doing what it's supposed to do.
Okay, time to get serious, what is the actual problem you're running into? Tight squeeze? Bad angle? Can't get any torque to get the nut off?
I done that counted to 10, and now to 100.. it very tight, I can put my finger s can touch it but I wonder if the a/c compressor need to be loosen it to get the nut out? I saw couple of YouTube video on the 2016 mustang gt..
Yesterday I when to Sears and picked up a set of gear wrenches for $27.99 it on sales, I was thinking about craftsman set gor $74.99 but I go ne in a cheap route.
It's my understanding that removing that A/C line is what is needed to make it easier. That's coming from a local mechanic that installs a lot of headers for Houston S550 members.
I have installed ARH full system on my GT350. The A/C area bolt is the tough one as you have discovered. I used S shaped gear wrenches.That alone is not enough, you can get the wrench on it but to turn it requires creative thinking. I believe I used a long extension to "push" on the s wrench after I got it on the bolt. Then repeat. That bolt/stud is time and patience consuming. Forget even thinking about getting a torque wrench in there to set it. Just tighten till you know its tight. PITA
Studs have to come out. Be careful removing studs from heads. Back them out a 1/4 turn at a time then back in a little. The last thing you want is galling on the cylinder head threads.