Okay, so tonight was the night that I was going to max out on squats. Went into the gym and did so. I was winding down my workout with 385x1 and 405x1. I got 385 with about an "8" on the strain scale. I thought I had more in the tank, so I went for 405. Long story short, I got pinned about 4-6 inches out of the hole and my upper back started rounding.
So to get to my question, I know that I'm weak out of the hole and my upper back rounded. What assistance exercises should I pick to help get rid of those sticking points? Any help would be appreciated.