I built 2 Solution X's about 9 years ago. I widened the fuselage 1" to accomodate a 3W 4.2 twin a friend of mine had. I used a G-62. I started at the cowl 1" wider, and decreased that measurement 1/8" at each bulkhead location going rearward. That way at the tail I was only about 1/8" wider that stock. Turned out nice, and built both in just a couple months. They flew well. Mine was very light with the G-62 on ignition, and weighed 18.5 pounds. Not hard at all building the cowl out of wood, and no worry about paint match. Scott