Few of the head fairings are quicker than the newer TT helmets anyway. I've done analysis on quite a few and only found one (Giro Rev IV) that's quicker than the fastest safety option (for me, a Giro Selector with the wedge), but my visor kept coming off the Rev IV and eventually the straps always break off so it's no real problem. Only a couple of watts anyway.
As for getting faster - yes intervals. And have a chat with people in case you have a horrific position as well, huge gains to be had there regardless of fitness
Few of the head fairings are quicker than the newer TT helmets anyway. I've done analysis on quite a few and only found one (Giro Rev IV) that's quicker than the fastest safety option (for me, a Giro Selector with the wedge), but my visor kept coming off the Rev IV and eventually the straps always break off so it's no real problem. Only a couple of watts anyway.
As for getting faster - yes intervals. And have a chat with people in case you have a horrific position as well, huge gains to be had there regardless of fitness
Xav