My DB GMG came with the one piece heat shield.  My DB was manufactured in 2015 and I got it as a gift right around Christmas time. I have tried over and over to get steady temps from left to right. My heat shield never came with the slot so I modified it to make one. Still though I could never balance it out. I called GMG and they sent me a new one. I was amazed at the difference in the hole patterns from the old vs new one as in the picture.  I installed it to what I thought was the right position and nailed it off the bat!!  Temps from left to right at 170 even, when I went to 190 and both sides even, 210 and even, 240 and even. Pretty impressed as I was even thinking of drilling holes in the heat shield, but the new style has worked great so far. Kudos to GMG!!

which one is the new one...JK.  Love GMG CService

 Such a relief!  Just imagine the time spent developing the new heat shield..Good of GMG to stand behind their products... Just an other example why todays pits are better.

I have the old heat shield in my DB that I bought 2 or 3 years ago.  I don't know if I want to fool with a new one since I have got mine pretty close with the longer notch.