It Will be fine, Ive got on with a os 46 with standard muffler and its wicked!.Try a Zinger 12/5 prop ( flair do them) great acceleration an fantastic brakeing. As you have the kit version make sure you round the fuss of properley if you don't the you will need nose weight,you should have about 3 eigths of an inch of the balsa triangle showing mid way between the T.E of the wing and the L.E of the tail plane and on the top tapering to none showing by the wing and tailplane but on the bottom the 3 eigth continues to the end of the fus. Mine is glassed with 3/4 oz cloth, one coat of epoxy and not rubbed down and it ballances perfect with a 400ma nicad behind the tank.

Hope that helps
jason