My Suburban was lowered with a Belltech kit including the notch but would still bottom on hard bumps.
It was converted when I got it and they had used those red urethane pancake bump stops which is stupid. It was just like hitting the frame! They have no cushion at all.
After some debate I purchased a set of
Bel Tech bump stops. They are actually a little to long and I was going to trim them but decided to just run them and see what happened and I LOVE THEM!! No more frame rattling bottoming out. They cushion it perfectly and I have yet to even feel it bottom out. I am sure it does but they absorb the blow perfectly.