When I swapped our 2008 FL2 to a 2010 engine, I never really registered swirl flaps. I swapped engine looms so that the later engine uses every sensor and the original ecu from the 2008 car. No fault codes showing, and it all runs well.

As I am want to do yet again changed my mind. So damned cold outside so decided to stay in the garage and remove the swirl flaps. Couple of hours later and copious amounts of carb cleaner manifold is now ready to go back on.