What to believe, Tachs & throttles or Synch gage?

[bajabruce]

I have twin 350XL Crusaders. Pretty much through the whole RPM range, if I match the RPMs on the tachs, the throttles are in line. but the synch gage shows that the port engine is running faster. They sound like they are in synch as far as what I can tell. I know there is a procedure for adjusting the synch gage, but want to make sure it is not a tach problem.

So what do I believe, the tachs & throttles or the synch gage?

Thanks!