I've known several people that have had the Hypercharger on their bikes, both evos and twin-cams, and the type of problems described above were never an issue...
I've had this problem whenever I had a headwind of more then 25mph at highway speeds, which is why I've since switched to a se a/c now.
this was on a evo engine.
the hypercharer now is mounted to a pic frame hanging on the wall, (I had a custom machining done to it for free)
i've put about 92,000 on one w/my flstc w/no problems or performance issues that i know of. get'n kinda tired of looking at it now and thinking of put'n a big sucker on.