It has been a while, but I think the Eagle mod is what one of the airplanes that I flew had. It Sucked! In case I have the name of the mod wrong, it was basically a bubble put inboard of the wing, extending the wing and the fuel cell. Its benefits where increased lift and increased max t/o weight. But, you lost a little in the max payload and you lost airspeed which isn't good on a Citation. The extra fuel you could carry was needed to get to where you wanted to go. That would off set the additional weight you gained on takeoff. Essentially, in the end, all you had was a longer wing that got you there slower.
I did, however, like the mod that removed the aft cabin cargo and added a cargo in the tail cone. This was much more comfortable for the passengers. But then again, I rarely couldn't fit all of our baggage in the nose cone, save a couple hunting trips. I don't know if this was technically a mod, but it was a great way to get our pax some extra leg room.