I just retested with the driver’s springs bypassed (as in the previous pic)- I’m getting 25 Amps at the tail cap now!! That’s with a Vapcell P54 26650, a GoLisi S43 26650 is slightly lower - around 22 Amps.
So the SFH55 should be hitting close to 7000 Lumens now- going off the graph in this thread 
LED test: SFH55, 6500k
