I just took off Os46 this week and replaced it with a Magnum 70RFS and the plane balances perfectly at 4.75" with the battery at the back of cockpit and receiver in mid of cockpit.

Yeah I had to make a brass nose cone for mine on my lathe for the 46 to get it to balance. I have it down stairs and can weight it if you need. This plane is obviously meant to have a 70 FS as shown in the directions. As for that I am starting to believe every plane out there is really intended to have the largest motor recommended. They only give a range of sizes to accomodate everybody's wallet.

Just got back from 3 tanks this morning and it flies great with the 70. Still breaking the motor in so nothing to crazy today but it is always fun to put the flaps down and watch this plane leave the runway in about 10 feet flat and level. Oh yeah, gotta love that 4 stroke purrrrrrrrrrrrr!