912ULS low gearbox friction

Hi all,

I have just done my engine annual. When checking the gearbox friction torque, I found it is 32.3Nm, within limits but too low for my taste. Later, when I synced the carbs, I realized they probably where quite out of sync before becase I was able to reduce the start & low rpm vibrations by a great deal (previously I thought those were normal, I guess you do not realize which is an abnormal vibration until you remove it).

It is difficult to describe "how much" an engine vibrates, but let's say before my sync, when starting the vibrations were clearly noticeable, specially when cold, and very obvious when the engine ran without the cover (because you could see the carbs shaking). After my sync, now there is almost zero vibration (there was a little after syncing even with vacuum gauges measuring equal, but reconnecting the compensating tube it was reduced it even further).

My question for you (more experience & helpful people :) ) is: could that low friction value come from carbs having been out of sync for long?

The engine is still low hours (343 TSN) and I own the plane since it had 272. One year ago, in December, it underwent another annual but sadly it was not done by me and I do not have the friction torque measurement. I usually do long warm-ups, trying to care the engine, but I always try to do them at high idle (2500). Propeller is fixed pitch (DUC Swirl-3, which AFAIU is relatively lightweight). 

My plan now is to fly it normally, as value is within limits, and check it again in next anual (a year from now, which by my flying time should put me in the 400h range so that will be a big revision). Does it sound sensible? Or would it be better to re-shim it right away?

Thanks in advance,

Carlos