Hey Grant,

I think I can answer that question. The PFS and DFS are different level-staged documents that reflect a mineral project's economic viability. The economic analysis from these documents show the potential viability of a mineral project. When preparing these technical reports the framework can be similar such as geological, engineering, and economic factors but the level of detail, precision, and confidence results in a vastly different outcome of these studies. In expressing the above I believe in my opinion the reason for the huge difference is a result of a few factors:

PFS

-Allows for an inferred resource to be included into a PFS document (huge difference in economics)

-PFS did not have 171 MT of Waste within the Block Model

-Had a negative cost to produce a pound of Copper (Lower strip ratio, Lower operating costs, higher recovery rates of the metals)

BFS

-Includes only the M&I resource Category

-171 MT of Waste rock as a cost rather generating ore

-Roughly 40% of Paramount (Higher grade mineralization) outside the Pit Shell

-Current DFS has Lower recovery rates for metal extraction

-Current DFS has higher operating costs, higher strip ratio due to waste rock within the Pit Shell

PFS (old) vs DFS (current) comparables

1) cash operating costs are US $12.49 per tonne vs. $13.33 per tonne-milled

2) The revenue generated by all the by-products covers all operating costs and adds a credit of (US)$0.32 /lb of copper produced to the revenue stream. Thus, a negative operating cost for copper is estimated vs. LOM copper production total and cash costs per produced pound including mine site operating costs, smelter and refining charges and concentrate transport cost average $2.09/lb and $1.15/lb, respectively.

3) Cash Operating Costs are estimated at US$12.49 per tonne of ore for the life of the mine. Average costs are US$4.14/t for mining, US$3.94/t for milling, US$0.93/t for general and administration, and US$3.49/t concentrate handling and treatment vs. Open pit mining cash costs average $6.56 per tonne of ore mined, including waste and ore mining costs.

4) the annual stripping ratio is estimated at 1.88 to 1 vs. The in situ life of mine average strip ratio (waste to ore) is estimated to be 2:1.

5) Mill recoveries are projected to be: copper to the copper concentrate: 88.4%, molybdenum to the molybdenum concentrate: 71.3%, gold to the copper concentrate: 81.3%, silver to the copper concentrate: 70.7% vs. Metal recoveries to the copper concentrate containing at least 28% copper content are expected to be 86.6% for copper, 73.0% for gold and 48.3% for silver. The molybdenum recovery to the molybdenum concentrate (+50% Mo) is estimated to be 58.8%.

6) Total initial investment in the project is estimated to be US$2,950,406,000 vs. Initial Capital Cost ('Capex') totals $3.256 billion, which includes contingencies of $374 million

7) LOM of 23 years vs. LOM of 21 years

8) A Measured and Indicated Resource of 1.393 billion tonnes vs. Proven and Probable Mineral Reserves total 940.8 million tonnes

9) The Exchange Rate used throughout the report and this News Release is one Canadian dollar = one US dollar vs. at an exchange rate of CDN $0.96 to US $1.00

10) the mill is expected to produce 4.76 billion pounds of copper, 255.2 million pounds of molybdenum, 4.5 million troy ounces of gold and 32.5 million troy ounces of silver. Rhenium is recovered in the molybdenum concentrate in significant quantities. At a present price of $350 per gram of pure rhenium this may represent a significant additional contribution to income vs. Life-of-Mine ('LOM') metal production contained in concentrates totals 4.88 billion pounds ('lbs') of copper, 4.21 million ounces ('oz.') of gold, 214.92 million lbs of molybdenum and 25.10 million oz. of silver

Note: Proven and Probable Mineral Reserves total 940.8 million tonnes containing 5.6 billion lbs of copper; 5.7 million oz. of gold 363.5 million lbs of molybdenum and 51.7 million oz. of silver

Overall the Waste rock is very important conponent in improving the life of the mine, strip ratio, lowering operating costs, and overall greater economic NPV that I think could significantly improve from current numbers.

YM