I have the P-Flo and, with its K04, its trims typically sit at +7% (warm months)...but trims (multipl./long term - off idle) can creep up toward +10% during the colder months.
Neuspeed's older P-Flo was worse; with its MAF position much closer to the down-turn just prior to the turbo.
My warm month (US)mpg is 30 mpg (30.2: over 650 mile average) currently; 36 mpg (Imp.). I have difficulty keeping its mpg above 29 mpg (US), 34 Imp. mpg, in the cold months.
I've considered swapping to a CTS intake, but I really could be gaining very little for doing so. And this makes me think to just stay with what I have.
I know there was a good bit of hype being spread, regarding the REVO intake for some time. But in the 80+ page "Topic/Thread" where the trims were being shared, the REVO trim reports were all near the +15% mark; ±2% to 3%. I always thought if the transition in the REVO tube were further upstream, then maybe the laminar air flow would have settled better. But that's me being suspicious of the transition in their tube; just prior to the MAF and possibly disturbing the airflow at the MAF.
I know GIAC worked with EVOMS in correcting their early production period woes, regarding fuel trims, and it seemingly paid off. Sadly though, EVOMS has discontinued production of their MK5 intakes when sales for it dropped. EVOMS; another I considered.