Barbara,
That's a really nice drop from that 521.
Yes, she can drop that much, but, are you 100% sure that 521 wasn't a wonky reading?
I think when your scale was created, the high end was based on what sort of numbers Thumper had been getting recently. Robin probably didn't think she needed to worry about 400-500+ numbers.
It would make sense to shoot a little more at those numbers, but if the 521 was a bounce, then you wouldn't "shoot the bounce" anyway. If she starts regularly throwing out high (like THAT high) numbers, then we can figure out a higher end for the scale. But I don't think that's going to happen myself.
If she drops just another 75 points at +6, that'd be great. Probably not too low to cause another bounce. I think if she can avoid bouncing from tonight's cycle, you should see a good AMPS tomorrow. Fingers crossed!
Carl