The hard lowers are shaped so air cools the engine, regardless of the opening. The vent is for the riders comfort. The soft lowers do not provide that air flow, that is why you need to remove above 55 degrees.

The 14 up hard lowers are well designed. As others have said. To each their own.

 

Show it to me in writing. No where does the Mo Co make that statement anymore. Yes, years ago with the Evo and twin cams that were running dino oil, air flow over the jugs was an issue. Ever notice that once the Mo Co came out with Syn 3 the "Do not use above 55 degrees" statement went away. The disclaimer is no longer in the yearly catalog they put out nor is it in print as a part of the instructions that come with the new design soft lowers. There are some here in TX that use them year round without issue. I'm one of them. They have a rubberized backing so if its raining, they go on.