Yes the A/C on the SERG is a high flow. Compare it to a new SEUC and you'll see the difference. Also, the MoCo now sells it as an upgrade for other bikes...
Screamin' Eagle® "Ventilator" Performance Air Cleaner Kit - Chrome
Stylish low-profile exposed element air cleaner kit provides increased airflow to boost the power of your fuel injected engine. The track-inspired exposed element adds a purposeful look to the bike, and the included waterproof rain sock protects the filter during inclement weather. This easy-to-install kit includes low-profile air cleaner cover, high-flow filter element, back plate, Screamin' Eagle® badge, protective rain sock, and all required installation hardware. Street legal when used with stock mufflers. All EFI-equipped models require ECM calibration (priced separately).
29490-09
Fits '08-later Touring models. Also fits '09 FLHTCUTG models.