in your earlier above post you said you were running a 16X6... in the last post you say 15X6...[X(] which is it ??
if you want a better 3d prop try a 16x4w apc......if the engine can't spin this prop with authority , try a 15/4w apc...this will slow you down quite a bit !
your right about the weight in the tail, obviously the ideal situation for 3d would be no weight at the ends (tail &nose) and the battery servos and tank at the cg.....but that ain't guna happen