I did some back to back testing on my own 209 SG 107 that made 123/121.. I tested the S&S dual unit, Doherty billet, SE heavy breather, and SE high flow, and Whimmer better sucker and CVO oval air cleaner. Kury street sleeper,
Out of those on my own bike looking at not only peak power but also KPA readings The only two that had roll back on KPA where the SE std high flow unit ( cotton with blue rubber) and the CVO unit. The CVO unit with the thicker K&N replacement filter solved that issue. Since that test we have run some others but nothing has really created issues other that the stock CVO unit and Stage 1 SE unit for bigger builds.. A stock CVO 110 + bolt in cam with the stock filter will not run 100KPA . I just got done tuning one. It would hit 100 KPA until aprox 3500 and the roll back to 95 KPA and by 6000 was at 92 KPA.
Simple fix really buy the K&N and go.