Okay, so I received the OEM seal and installed it today. The mopar/oem seal is built so much better than the Fairchild one. The rubber is thicker, and it just feels much higher quality in general. I don't know why, but even the "new" old header I bought does not sit completely flush with this one, almost like my top is too tight or something and pulling it back. It does definitely fit better though and is even. However, I did use a rubber washer as a shim where the header latch hooks in and was able to get the clamps to close tighter and now it sits pretty much flush with the seal. It doesn't compress that ridge that the header sits on though, is it supposed to?
No one on the interstate this late at night, so I decided to torture test it. There's basically no whistling anymore even at 95-100 mph. I could comfortably listen to music, have a normal conversation with my passenger, etc. (keep in mind I'm bone stock to the tire size and have all seasons and the tub, doors, etc. are fully sound deadened)
It's very nice. I'll have to see how it does next time I'm driving into a very strong headwind. Sure it won't be long with the crazy weather.