When I built my Extra 500, the instructions were pretty much useless, it was like they had mixed up several airplanes when they were writing them up.

Anyway, The nose gear was too short. I needed to put on a Fults nose gear unit. Otherwise it was nose down and you couldn't get it to lift off before you ran out of runway. This in flying off our grass flying field, no pavement. I also put on larger diameter wheels too.
After fixing the nose gear then it flew great, it only needed a little trim. Because it has a semi-semetrical airfoil you can pull back on the throttle and cruise around nicely.

I mounted a Fox Eagle 60 inverted, and because the engine was fairly light, I needed to add some lead to get the CG about right. I also used a magnetic pickup so I could hold the blind nuts on the inside and get the motor mount situated and bolted down. My hands were too big to reach way up in there.

The plywood where the rear landing gear mounts to isn't glued all that well to the fibreglass fuselage, so you should add some fibreglass tape and epoxy it in more. One not so good landing and the landing gear pops loose.
Now the rear horizontal stabilizer is up high and as such it is more or less out of the prop wash, so it could stall out if you slow down too much, then the plane will have a tendency to pitch down on you (drop the nose), so don't try coming in too slow.