I have read in a few places (here and on the color classic faq) that a 575 Logic board can't address 128mb Simms because they're not single banked. But I just ordered a 128mb Simm from 18004memory.com and installed it in my Mystic and have a total of 132mb. Just thought I'd share.
Here is what I ordered:
Now I'm off to test the difference between 20mb and 132mb...