When talking with an HD rep a while back, he told me they took them off because of leaner AFR and engine heat issues. I was told to go ahead and run it but if outside temps are above 90, I should take it off. (Don't shoot the messenger). So, this made me ponder the issue. Since it really just pushes air down way up there on the forks, I could not imagine how that would impact engine temps. Anyway, I tried in on my 09 103 SG after making notes on how hot my engine ran in relation to outside temps. Guess what? It didn't impact engine temps a single degree and it kept some of the hot air off of me as well as the cold air in winter. It is there to stay. This summer I hit a high outside temp of 130.4 according to the local weather station as I passed by Lake havasu. No, my motor did not melt down. I think the heat story is one of those "old wives tales" myself.
jb