40-size Fun-Fly, ARF, and 4 lbs finished weight! Don't we all wish <LOL> Its just not going to happen in an ARF. Your dreaming! Like I said, we are all looking for that 4 lb Fun Fly, which is awfully tuff to achieve when building a kit, thence an ARF of that weight is almost virtually impossible.
Good Luck! BTW, the TTs are notorious for being some of the heaviest ARFs in the industry.
Sorry, but there is no solution that I am aware of.
Kevin