I've got the same model (I'm almost possitive) and I've been told that 50-60 PSI is the recommended level. It's hard to get any more 'pressure' if you're running it straight from the tap, but what you can do is tap off the entry point into the house where the water pressure will be the greatest. I did this on my hot water heater(HWH), on the cold side. I simply shutoff my water coming from the street (there's a shut-off valve right on the cold pipe going into the HWH and then added a T with a threaded pipe fitting on the end for the RO
unit to plug into. Right before the fitting, I put another shut-off valve so that way my main water can continue to run into the house, but when I need RO
water, I simple turn the valve about 1/4 of the way open (PLENTY of pressure, trust me) and then it also feeds my RO
unit at the same time.
It's kinda hard to explain the details of how I did it, but be sure to look out for a post on my new Stored Water Resolution. I made a unit to store water in my garage into 2, 55g plastic drums and ran my RO
unit to it along with electricity. I'll be posting some pics real soon.
If you want to know more on how to do this, let me know and I can scan my diagram that I used to design it (nothing fancy, only in pencil).