I recently traded for a couple planes and ended up with a Como S .90 engine. It is nice and tight and doesnt appear to have run much. It will be going in a P51 that the builder set up for a OS .90. The OS mounts are further apart(or at least that is how he attached them) so I will need to do a little work to mount it. My question is - I also have a OS 1.20 4 stroke, is the Como a good engine or should I mount the 4 stroke?