SkyDemon ,,,
The *best* info given so far has been what Ed Moorman has given...

Unless you have the experience to fly performance twins AND to
do major repairs,, using the .46FX on a Twinstar is HIGHLY **NOT**
recommended...
If you look into the multi engine forum at the *Official Twinstar *
thread just about all your questions will be answered there...
http://www.rcuniverse.com/forum/m_26...tm.htm#2688899

I have done Twinstars with just about everything from .25LA to
doing what I named the Phoenix that uses .52 TS motors... I
can tell you the smaller motor'd ones fly soooo much nicer,,
and would be better for a lesser experienced person to fly and
LEARN with...

As Ed noted,, the more motor that is used the less flying time..
Plus with hot motors an engine out will rotate the plane rather
quickly...

The Stick that Ed suggested is a good plane for the .46FX's..
But it will be somewhat of a hotrod... I flew Ed's and that
thing is rather fast,, and a total blast...

Something to think about is maybe doing up a Great Planes
60 size stick... Attached is a pic of one I did and it flyes like
a dream.. The three bladed props were ONLY for looks as
it was made with more thna enough room for bigger props..
Isn't a rocketship,, but is a great flying plane..

If you want to do a Twinstar then I would highly suggest staying
with motors in the .30/.35 range for good all around flyability...
If you want a plane for the .46FX's,, do the Stick thing...