I also have a chargriller with a SFB with no mods (I just raise the fire grate so it is not sitting in the drawer). I do however, have grate level thermometers on both the left and right side of the grill.
I start my fire with kingsford coals arranged in a circle about three levels high with cowboy hardwood lump charcoal in the center. Once the flames die down I am at 225 in the main chamber. add wood chuncks and i'm off to the races.
DISCLAIMER: only my third time running it today but all three times it has been this consistant.
Either way, good luck!