Thanks. I tried a physical limit but when Helix turn on, it recalibrates and creates a new dead zone, now with the new resistor value as max. That now is 100% and takes some travel to go to 99%. The limit was originally set to keep the pedal at 99%. In any case, I'm not quite sure if the helix recalibrates "on the fly" as (I need to confirm) the limit seems to lose the effectiveness after a while, even with the device on.
I think the EX-1 has a 10K pot. my Bespeco have a 20K pot. Both pedals works ok within parameter range, both have similar dead zones, so, the helix is capable to calibrate different pot values. With my additional pot (5k), the max value on the bespeco went to around 24K, calibrate to 100%=24k, down the pot to 99% with new value of resistor (it went to around 21K. It is the electrical equivalent to a pad) and seems to work, until it doesn't and the dead zone returns at the new max value. I think is not necessarily a mechanical or electrical limitation of the pedals but maybe the calibration routine of the helix.