Hi Tim,
All of the mods that Cyberwolf mentioned goes a far way in making the Extra more structurally sound especially to take the vibrations etc. of a gas engine. The CG Extra has a tendency of sometimes nosing over when taxing from a grass field and holding a tad of up elevator sure helps but I found that adding a 3/8" thk. to zero wedge plate between the alum. landing gear and the fuse which give the main wheels a forward rake of about an additional inch cures the problem completely.