I read somewhere that somebody was actually mounting their engine to the bottom of the cutting board engine mount. Which way works best? I will be installing an enya 40 to a spa3d tonight and I want to make sure it's right. Thanks.

Also on the QHOR with the 36" wing. Is anybody installing stiffners into the wing?

Look in the QHOR & SPA3D thread.

The QHOR has the engine mounted from below, the SPA3D has it mounted from above.

Basically, you do it whenever you can, because it's easier, but sometimes something get's in the way.

The reason given (by Tattoo, I think) for mounting the engine on the bottom of the board is that it can be mounted that way without having to remove the muffler.

Either way is fine. It doesn't matter from a thrust line point of view. I'm using carbon fiber stiffeners in my wing, but some others are using music wire.