I assembled it per the instructions, and put the battery in front. No extra weight was added. Turning the gear around was the only mod I made. It makes ground handling much easier. I put the 46 in mine, because that's what I had laying around when the plane was given to me (Christmas last year). It turned out to be a nice package....and it's plenty fast. I cut the pitts muffler tubes off short, and added a pair of silicone extensions that hug the underside of the cowl. Looks nice. I've got to say that this is one tough little plane. On it's maiden flight, I cartwheeled it down the runway trying to takeoff, and once I slowed it down too much on landing, and it pancaked from about 5 feet....not a scratch on it....tough little plane. If I ever total it, I'll buy another.