I had an OS 46FX in my Rascal 40 with Great Planes 40 size floats. The 46 was plenty of power. I was unable to get my plane to fly with the floats. I think the CG was off, and the plane was tail heavy, but it balanced perfectly according to Sig's CG. I almost hit a boat I used the stock OS exhaust and cut an "oval" in the side of the cowl. It fit perfectly. I'll post a pic if I get a chance (someone is coming to look at the plane this afternoon).