I have a MES 40 new gen. After reading many things on this forum, I decided to do the mailbox modification. I started out with the flexible tubing (for dryer) and set the mailbox on a brick on the ground. I didn't like the idea of bending over to check on the AMNPS, so I put a shelf bracket on the side of smoker and mounted the mailbox to that. The alluminum mailbox was $15 at Menards.
I took a piece of straight vent tubing (also alluminum) and cut it down to the size that I needed to connect it to the hole in the smoker where the chip loader goes in. The 3" vent tubing fit perfectly
in that hole. I took the chip box completely out. I have never used the water pan, so that is not in there either. I have put a 90* elbow on the vent on the side of the smoker, with no extention. That also fit nice and snug on the existing vent apparatus. I had to wrap the 90 with foil for a few smokes because it was leaking, but after a while it sealed itself up. On the back end of the mailbox (towards the top) I traced and cut with snips a hole to fit the vent tubing in. I used the flap method to attach them together. I've done a few smokes with it so far, and all I can say is that this system is the BEST.
The pellets burn the way they are supposed to, and I can see the kind of smoke that I want to see coming out of the vent. It's also very easy to check on the AMNPS without opening the smoker door.
The mailbox has small holes for mounting, that lets air in from the bottom, and I also drilled one 1/2" hole in the door. This is a great forum to learn from!!!! Dave.
ps. I also hooked an Auberins 1503 1800 watt capacity PID. I did that a while back, and I'm glad I did. That mod is quite expensive. $200 +