Andy,
The ideal casting weight for a rod is one ounce per pound test curve, plus half an ounce.
So your 2.75lb would have an ideal casting weight of 2.75 + 0.5 = 3.25oz.
This is a rough guide and depends on the taper and build of the rod.
As mike suggests, a loaded method feeder will weigh about 6oz, consequently you are not casting, but lobbing this weight.
Any attempt at further pressure would probably shatter the rod.
If you were to compare casting distance on the reels using a 3oz lead, then there would be a difference in the distance achieved.
My suggestion to gain further distance would be to cut down on the amount of mix you are using around your feeder, so you are then casting a lighter weight.
Obviously if you are starting to hit your casts hard, then a shockleader would be required, I suggest ESP 15 to 45 tapered, keeping the joining knot very small and neat to allow the feeder to pass over it and not render it a tether rig.
I hope you bought those reels cheap, shops are chucking them out for about ?120 now........