Bill,

 

I just got the new Kitplanes with the Legacy FG on the cover.  They mention that putting the larger engines on the FG would require an $8,000 carbon fiber upgrade.  The reason given is the original structural testing with the heavier engine was done on the carbon fiber airframe.  The author of the article comments that if you want the bigger engine and buy the carbon fiber upgrade, you might as well build the retractable version.

 

Mike