There is a guy doing conversions out there and hopefully he sees this thread. It would be great if he could share his Force One's performance with us? I also believe his Force One does not have retracts.
I have a Byro Enforcer as well and I don't think I would go any smaller than a .65 on it. I have a .77 on mine and I just finished building one for a friend andit has a .91.
It might be ok but I don't think the .45 would be big enough for the Enforcer...?
The Force One I saw has the power setup just like you would expect between the tail feathers but there is no ducting so the engine/fan/pipe sit right on top in the open. Easy maintenance 'eh?

Oh, I think the guy said he was going to start selling the conversion package for this I could be wrong though!

Now....if I could just find that URL!

Myles