ORIGINAL: RCKen
bigdanusa,
What plane are you building? Check your instructions/plans first. A lot of kits/ARF's/plans will have the right trust built into the plane itsef, but usually have to add the down thrust. If you do use it, you can add it in by putting washers between the motor mount and the firewall.
Hope this helps.
Yes... Most ARF's have the right thrust built into them... If needed...
I doubt those two Airplanes would need downthrust... (Doubt, don't know for sure)
Matt