If you can fit a shorty manifold that will flow nice it is definitely the best way to go. When I say flow nice I mean the bends have to be as gentle as possible, and absolutely no cheating of the entrance to the turbo manifold. In all honestly it doesn't make that much difference from long vs short, engine build quality will way out weigh it.
Check out this SWEET Rx-8 turbo manifold we pulled off a customer's car..
Curious to see how your EFR works out, I've got tons of guys asking me about doing those..