There isn't alot of significant size difference between the .40 and .60 size. Another club member had the .60 size.. and you have to get pretty close to realize they're different sizes... The first time I saw the .60 size I had to look at it for a while... even sitting next to my slightly smaller Extra... and this is even after building 2 .40size planes..

I've always liked the way this plane flies... its always felt bigger then it is... and still fits inside a car(although I don't drive a car..haha..).. it takes up little space storing it also.. just take the wing off and it will sit out of the way in any corner or shelf.

Keep up the good work on that build.. and about the wires.. I don't know that would go without them myself.. once bitten, twice shy in my case.. but.. whatever you do.. take it easy on shaping the stabs leading-edge.. don't take off much if any material.. and only flat-sand what you need to make it true.. You want that as stiff as possible.. regardless of what engine you run...

Although the .46 won't have the vibes and torque the .91 does.. I'm sure theres a reason they spec it at a .46 or so 2-stroke.. and if I'm not mistaken.. the max 4-stroke they spec is a .70. I'm a glutten for punishment though(at least when I built these Extra's).. I imagine if GreatPlanes says "good to go" with a .46 you'd be OK without them.. probably not worth re-inventing the wheel.. but they didn't say "good to go" for the .91.. so I had to re-invent it if I wanted one with a .91.. and I don't think I'd change a thing..

Regardless.. have fun and learn.. that's a great kit to learn with.. and you'll have a very nice flying model when done.