More and more manufacturers are recomending WOT Break- In method.
After reading a post by Andrea Rossi in Sirio's web site, this is the correct Break-In procedure for the S12's

1.- One (1) tank in the bench at WOT with very rich setting of HSN, avoiding it to go on 4 stroke.
COOL DOWN
2.- Three (3) tanks on the track with very rich setting of HSN, and tuning the HSN at the end of third tank to get almost full power.
COOL DOWN
3.- For 20% Nitro, use .20 head shim and N° 7 Glow plug.

He says after that, the engine will give more power after every new tank.

Which means that Breaking-In Sirios, should be done with more or less 300 to 500cc of fuel.

AFM