I’m building a Sig LT. It does not recommend a triangle support to help hold the stabilizer or fin on. I remember adding this on my CG Eagle. Should I add something? One side or both?
Also, I have a little left thrust and the directions say center or a little right. Can I just put some washers between the fire wall and the mount?

yes and yes.

You can if it makes you feel more comfortable with the build.

I built the LT-40 and have two years of flying on it without issue and didn't add the triangular stock. Long as you get a good glue joint you should be good. I used epoxy to secure the tail feathers to the fuselage. Also put the glue on the fin and woodpeckered it into the balsa with a needle to help it get a little better grip.

somegeek