I know I was confusing as hell on that last post...I suck at trying to explain this sometimes.
Nothing is wrong with 14-15:1 AFR. I meant to say that the cleanest burn emissions wise (least pollutive to the environment) occurs at stoichiometric ratio of 14.7:1 AFR.
You will obviously get better fuel economy if you run higher AFRs (i.e.17:1 at idle), but you also run the risk of getting knock and high EGTs. That is why you need to tune for those things when dialing in your fuel and ignition maps. If you have a standalone, obviously.
I agree that blow-thru is the way to go but for some reason it reads a higher air flow rate (higher voltage) than if it is a draw-thru on the same setup. So you max the MAFS out at a lower hp than with a draw-thru installation on the same setup. Plus, plastic MAFS housings on 25 lbs of boost don't tend to hold up to the heat and pressure. They either crack or you tighten the couplers down on them so hard that they crack anyways.
I still don't understand why recirculating would improve mileage noticeably. Maybe because people like the ricer sound of it and are a little more throttle happy than those that are recirc'd.
And drift925, it might lose power due to inefficient fuel use, but it is during an off-throttle event so it's not making power anyways