You will notice anyone winning races is wrecking loose coming off the corner so loose is good, but tight through the center and loose off at 51% cross sound more like a condition I dealt with, hopefully I can shorten your learning curve.
I was good on entry, had trouble rotating the center and getting back to the gas. Same as you. The all the sudden she would violently snap loose. So its was Tight, Tight, Tight, Whoa loose! First we thought we had to loosen it up, we went all the way to 46% cross and a 225 RR spring. Yes the car drove better, but I was still wanting it to be looser. That when my crew chief said he thinks its the entry which is the problem. We lowered the spring rate in the front which loosened the car up and we ran the fastest lap time we ever had at that track.
Of course we had go back to our original rear springs and our baseline of 48% cross.
I recommend Kevin Yeatts set up book. Its a $100, but it comes with tech support for the whole year. I bought it, didn't use it for the first half of the season (cause we were old Late model and Figure 8 guys, and we could do this on our own). We didn't make any real progress until we went to his baseline setup. I would say its worth $100 just to have his cell phone # where he will answer your questions.
Also check your rear tow and rear end square. These axle tubes bend real easy, just touch wheels with someone. If your rear end is not square you wont be able to drive it.