I took a KISS approach on my Herk. All 4 engines were set up using a protractor to get the throttle arm degreed in and matchine. Then Identical servos and linkage. I used a 4 to 1 linkage for just the throttle on the tx. to control all servos. Then Mixture is set independantly for each engine for most reliable setting. If the top is off more than 300 rpm you can adjust the ball link on the thorttle arm. All 4 cut off when the throttle is pulled to idle and (I have a kill button on my Micropro transmitter) I press the kill button. This has worked great and the 2 to 300 rpm difference doesn't even show up while flying. Good luck and happy flying.. Jim