Ok, still pondering building my own air/fuel separation system. Here is some info I have gathered from my 6.5L and Duramax. On the 6.5L the sticker says that fuel rate at rated horse (190) is 63mm/stroke at 3400 rpm's and the Duramax fuel rate at 300 horse is 91mm/stroke at 3000 rpm's. So using this calculator (Convert cubic millimeters cu mm - mm3 into gallons liquid US gal volume and capacity for culinary practise) I took the fuel rate X 1/2 rpm's (cause the IP turns half speed of crank on a 4 stroke... right?) X 60 X 8 (for each cylinder) to convert to fuel rate per hour. Plug that number into the calculator and we get a fuel usage at rated horse power of 13.6 gal/hr. That should be the rate if we pull the living guts out of it if I did the math right. So for the Duramax we hit 17.6 gal/hr. Interesting thing is we gain 110 horse using only 4 gal/hr. Pretty sure that extra horse at a max load level will make up the extra fuel usage within that hour, whole nother subject there! So here is my first major question... why do the major aftermarket lift pumps push 100 gph? Even at a increase of another 100 horse on the Duramax I can only guess we use another 5 gph which puts us at say 25 gph. I realize that to maintain pressure to the CP3 we need to flow more than usage but even at 30 gph that would be doable especially since we wouldn't be running WOT for long periods of time. Second question is is it possible to read the fuel rate while the truck is running, I only assume it is with a good scanner. If so can someone post those numbers, WOT and typical cruising would be the important ones. So back to the lift pump, it appears we only need a pump capable of about 30 gph at a few psi to supply the CP3. Now when it comes to a pump for the fuel/air separator usage from the info I could find you need to pump about twice the fuel usage rate so that half is clean air free fuel and the other half is the fuel going back to the tank with the air in it. That puts us at about 60 gph. Still much less than most of the aftermarket separators. Now, someone slap me for thinking about doing something this dumb and correct any of my math.