RE: Nitro models pusher Bobcat?
Heh, Expert? Not by any stretch of the imagination!!!
However I'm trying to help them out by writing a better manual for this plane and the Falcon 1.20 as well.
I have a few of these to play with so I'm going through the different interactions. I have over a dozen NP ARFs as is.
It sounds like you had the Nitro Models Bobcat .50. Is that correct? Did you get the one that is retract ready?
As posted here, the C.G. should be set to approximately 10.3"-10.5" from the leading edge of the wing at the wing root.
The plane will fly with the gear as it comes, but it is important to make sure that the attitude of the plane at rest on the ground has a positive incidence relative to the ground. If you don't do this the plane will not lift off the runway at run-up.
There was no need to change out the stab as you've done. Many here have flown it as is.