FYI, this is an update to my original thread which was in the SI Owner's Group. Wanted to get it out of just that group for everyone to use...
So I finally decided to drill the Warthog since I prefer to use the pellets over chunk. I looked at a few other posts where folks had enlarged the existing hole and/or added another one center-line under the element. Since I set my AMNPS off to the side of the element I decided to drill my holes where the AMNPS would be sitting to get the most direct air supply. In addition to drilling 2 additional 1/2" holes in the unit, I also enlarged the existing hole to 3/4".
End result - the AMNPS burns flawlessly now, either hot smoke or cold smoke and regardless of the food load in the smoker. No issues with keeping the pellets lit for the entire burn at all, good even TBS throughout the smoke. In retrospect, I wish I had done this modification earlier.
Here are the pics. Sorry about the poor quality, I had to take them with my phone.
Original center line drain hole enlarged to 3/4", 2 additional hole @ 1/2" ea
Top down shot with AMNPS in normal position foe my smokes
You can see the holes on the underside of the AMNPS here. I was worried that they would not be far enough out from center to maintain a burn on the outer row of the AMNPS, but I wanted to keep the holes within the drip pan perimeter to start. I figured I could add more farther out from center if needed, but it was not. Outer row of pellets burn just fine with the holes placed where they are.
I normally line the bottom with foil, this smoke was some CB so I just put a piece of foil under the loin and the SMNPS directly on the bottom with no foil. You can see the ash "foot print" of the AMNPS burn, I lit it from both ends and you can see the mostly empty middle row where there were no pellets.
Now I just need to cough up the dough for my PID and I'm set... Hope this helps those of you that love the AMNPS and were having problems getting it to run the SI units.