This is the issue I had as well, which made me switch to 5150. I might have to give the update a try.To echo the above,
I was accused of driving like a madman..
You'd try to accelerate gently in "D" and it would drop a gear, go full boost and light the tires up, you naturally back off, get back in it and then it will either go crazy again, or level off.
Now on 2.51, I can just drive normally in "D" for the most part.
Prior to the update, I actually thought it was easier to drive in "S" as I could modulate it easier.
Best $25 you'll spend this year.