I ran this engine a couple weeks ago and forgot to post my findings.. I haven't seen any other tach readings for this engine on this forum, and I searched all 34 some pages.

72°F air temp, 75% humidity
Italian SuperTigre S90K with stock "swing" muffler, clamped the farthest away from the cylinder, and stock ST carb with flat spraybar.
APC props
McCoy MC59 glow plug
5% nitro 20% castor

13x6 = 12,700rpm slightly rich of peak
13x4W = 13,400rpm slightly rich of peak as well (This prop had some major balance problems, so I will retest with a different 13x4W prop)

I have a mousse can for this engine that I'd like to try but need a header for it.