popping through the exhaust at 4500 rpm or so.. HELP!

Here's your pic that I modified. I've added hash marks for the needle stations and from that you can see that the SM ends before it reaches station #14. However, even with the piston all the way up, you should be running somewhere between stations #12 and #13, so I don't think it matters.

Interesting thought that the literature leads you to believe that it would have a true functional station #14:

Anyway, it's all academic at this point, right?