im looking at getting a wfp system very soon but wanted to know how much water the Pure Freedom Compact Reverse Osmosis System plus a 24v Aquatec Reverse Osmosis Booster Pump would make per hour.
is it
450gpd x 4.5 ltrs = 2025 x 2 for the booster pump = 4050 divided by 24hrs = 168.75 ltrs per hour
or am i wrong 
The stated productions of ROs are not real world figures - only hypothetical maximums.
What you get in the real world is very different.
For starters, I believe the GPD figures quoted are usually for American gallons. They are a bit less than UK gallons.
The quoted figures also assume perfect conditions (ideal temperature, water pressure, brand new membranes etc).
Obviously there can be considerable fluctuation.
I once used a 300GPD RO with a 75PSI booster pump. It gave anything between 450 and 800 litres per 24 hour day. There was a very long distance between mains outlet and RO though so this probably reduced it a lot.
You should easily be able to fill a 1,000 litre IBC in 24 hours with a 450 GPD setup and pump. If you are a single operator, that will be more than enough.
However, just bear in mind that the stated figures belong in fairy tales.