I removed 30lbs of soaked foam from my 95 X2. I replaced it with about 5lbs of pink polystyrene from Home Depot along with drains in the back.
The back of the ski floated just under water. The only thing keeping this ski floating was the air in the engine compartment.
Unless the 95 SXi's and my 95 X2 were made in different places, I'd venture to say it was the same 2 part foam.
I removed about that from my 96 SXI. It floated tail down in the water now it sits level about 2 inchs above water to the bondline. I am running no foam again after riding with out it last weekend!