Cajun,
the instructions for the plane the are here
http://www.spadtothebone.com/SPAD/Buhor/
What is the difference between it and the 2 mil built the same way
The 4mm coroplast has a lot more tension in it, and when the pressure is reliesed, the leading edge raises a little more, and it doesn't get as much undercamber as the 2mm wings. You have to do some serious clamping to keep the leading edge down while gluing

It also seems like the 2" of extra chord has made a huge difference in performance.
Rudeboy, man...them Coke and Mountian Dew graphics took forever to do!...and I didn't even get any sponsor money!

...but I simplified the graphics on my next one