thanks for replys to my previous question. have more. the tach wire is to be wired ,through the firewall,to the p-lead POST ON either magnito? (i only need rpm on one mag for now) or wire it to the mag switch post,that the mag p-lead hooks to,ON THE MAG SWITCH? also,the instructions say the prefered ground is TO the engine. this means to run the eis ground wire from the eis,through the fire wall, to the engine? how have others attached these two wires? (lycoming o-320,2 mags,carb.) thanks---lawrence---