Before you start drilling holes in it, just get a grate for the charcoal pan. All you really need to do is provide more air for the fire. These are designed not to be "air tight", and they're pretty good as is once you solve the coal pan problem. I use a grate I got at the hardware store. It's a little small, as it is exactly the size of the bottom of the pan. I solved this by making a 1.5" high "donut" of HD aluminum foil slightly smaller in circumference than the grate. Put the donut in the pan, put the grate on the donut and I'm good to go. I've had it hold temp for 6 hours so far. Might have gone another hour or so, but I was done so I dumped the coals. Only other thing you'll need is a good probe thermometer. The one in the dome is not accurate.
They're not adjustable, so plan your smokes for a 215˚-240˚ temp and you'll be fine. If you want higher heat, empty the water pan. If you want really high direct heat, just remove the water pan.
Good luck and let us know how it turns out.
