depends how you trigger the boost changes , on the eboost 2 i usually modify the gps to give a positive gnd point at each gear position and run 6 wires up to a connector, you can then select any combination of wires for each boost level , on the eboost 2 you can get 3 boost levels simply and 4 if you add diodes if setup for basic selection, and if setup for sequential a full 6 boost levels
but this is only of use if your pushing very high boost and want to controll it precisely , if your using 10 psi then 2 levels is fine leave the line at 6 and step up in 3rd
Eboost is not target seeking or closed loop like the ams, it runs a preset duty cycle on the solenoid and you get the boost that DC causes , its not quite linear , 20% dc does not raise the boost much but going from 60-80 will raise it a lot ,
A zx14 i setup is running at the events with us this yr and it has a eboost 2 , its running a 6 psi base spring and 25%, 35%, 45% initially which currently gives me around 14 psi and i will change as needed, probably up another 10% to make up for Bonnevilles altitude , that seems to make a difference to the open loop type controllers like the eboost and eueditor
I have a ams 500 for sell 200.00 Coby Adams does most of my tuning and I bought it and he don't like them so I used one he likes, don't know what it was. paid over 400.00 for the ams 500 but will sell for 200.