I am an instructor at my field and have also noticed the strong right pull of the Nexstar. I agree with those who say it is because of the large right-thrust of the engine. It does help a lot to do your take-off with a long roll at 1/2 or so throttle.

Another problem one of the students had was that the wing was very loose even when the wing bolt was screwed in as far as it would go. The wing would rock back and forth with a 1/4 inch gap between the bottom of the wing and the fuselage. We were very concerned about it coming off in flight. So the student replaced the rubber bolt mount with a sturdy piece of plywood and a metal blind nut. Now the wing is held on quite firmly.

Made a world of difference in the way it flies! Whereas it used to fly real floppy and loose (you know, wouldn't hold a track, couldn't be trimmed for straight, etc.), now it tracks well around corners and holds a heading. I think the wing mounting and taking some of the right thrust out of the engine are the best modifications to make. [8D]