AVCANADA

As has been mentioned above, struts, rivets, etc.
Unfortunately however, nothing that makes the aircraft fly any better at that weight.

I flew in one many years ago. Could hardly hold altitude when it was hot and muggy out. If you want to haul an otter load, buy an otter!

You were probably still using the power settings for the original weights.. I was witness to someone trying to fly the f8cking thing at 5600lbs at 28/18!! No wonder it was staggering around like a stuck pig. If you want that extra weight, you're gonna have to burn more fuel.

I'll agree though.. you want to carry that much more weight? Stop being cheap and get a turbine beav or otter

As for the question by the original poster. Have you gotten the info you needed? If not, I can track down a couple of numbers/contact information for friends in the industry who have performed the STC. IIRC as stated before, its a strut change, some added reinforcements near them and a couple of placard and paper changes.

Doesn't Pasco run their beavers on the whip amphibs with the up gross? I noticed all their machines had two bladed props, and both the skegs AND vertical fins on the horizontal stabilizers

I would cruise all day long at 125mph indicated with a touch of flap using 28/18

Ours had a 3 blade Hartzell prop and the full Baron STOL kit and WIP 6000 amphibs. I would cruise all day long at 125mph indicated with a touch of flap using 28/18

I think they complement each other. but the baron kit by itself didn't seem to make much of a difference other than stability in the flare and at low speeds. Was told with just the baron kit and the up gross that we should be running at 29/19