I also agree. Your stone looks too big and you're not getting enough airflow over the top. I have one of these:
that looks like it may be ideal. I'll find out soon enough once I fire up mine.
Originally Posted by Saiko
Thanks for the build pic, I have this saved now for when I build mine!
I agree with landarc here, from what I have read you need an opening behind the pizza so the hot air is forced behind the pizza, over the top of it and then out the vent. I bet if you opened that back area up and added HD foil to the lid you'd get much more heat down on top of the pizza.
Pies look great!