I’ve got the TR-J20 and did the resistor mod. Trustfire TR-J20 Update 8-11-14 The light get warm but nothing close to over heating. It’ll burn though 3-32650’s before over heating. Great light for a boost in brightness and swapping the XM-L T6’s for much newer better LED’s, Luminus SST-40 come to mine Mountain electronics has them Luminus SST-40 N5 6500K LED on Copper DTP MCPCB I would go to theses for the lower voltage used allows that current dipping draw not to affect the run time until the batteries were nearly dead. XM-L2’s and XP-L2’s at top bin would also blast just past the 10K lumen level nicely on a resistor mod using the original driver.