Dropping the 10k in as a filler stone might speed things up, but 150 laps on the arkie does not seem all that high. I have to do about 100-150 on my Cnat when jumping from the Norton 8k. Plus, aren't arkie's known to be slow cutters? 150 laps seems pretty normal.

On another note, how do you like the arkie? I've been thinking about trying out some some other natural finishers to compare them to my CNat.