I haven't had to make any mods and I can keep it between 225 and 240 with no problems. I put lump in the fixebox, and just cover the bottom of a Weber chimney with natural wood briquettes. I get 1 side of the briquettes lite and lay them on top of lump. I have both vents open to 5 until the temp hits 175, then I cut them both back to 2. I let the temp rise to 200 and then I can usually zone in on 225 with the top just below 1 and the bottom at .5
Hope this helps.
Char Griller Pro/ Char Griller Kamado