[Hectic]

Hop up mods do increase range, if yer gun can't apply enough spin to generate lift the shots will not fly as far, regardless of bb weight, velocity etc..
At 400fps you will want the black modify rubber with the promy bridge tensioner, the tensioner comes in a two pack, 1 hard and 1 soft, I haven't noticed much difference between them I'm pretty sure the black one is the harder one (squish test only) and I find if a hop unit doesn't have enough hop due to the travel of the arm or the depth it can enter the hop window then the hard one makes a difference as far as providing more hop.
Also at around 400fps when you have enough hop you will want to run .30 or better for bb's and you will also want to upgrade your inner barrel, a good hop up won't help much if the barrel isn't of smooth and consistent bore. You'll get the range but consistency will suffer greatly.