One thing I've noticed about guys, planes and engines, there's never too much power! H9 Funtanas w/1.00s, CG Utlimates w/1.80s, 80cc planes with 100s. Design your Ultimates for 40cc and 80cc and they'll be flying with 50s and 100s... I'll take a kit in both sizes! Good Luck and thanks for asking!

As far as 'removable surfaces', couldn't these be drawn in on the plans as 'options'?

TGP