I'll start a new thread with some construction photos.
My mate was installing the ES pipe in EF 88.5" Extra 300 and I don't see any problem fitting it to the Katana.
You'll probably need to move the rudder servo but other than that it would be in the bottom of the fuselage so it shouldn't cause any "problem".
For a first composite I wouldn't say so, then again I haven't built any other myself
