Interesting info and terrible oversight if as you seem to indicate the headrest cant be raised as in most cars?
On my ariel nomad we also had to spec the extra calipers for the handbreak, it was an option believe it or not, since the handbreak was not necessary for registration, they said well you can drive it for 3 years like that before the first MOT.
Out of interest, they also had a delete CAT option, same reasoning, just put it back on for MOT and remove it again afterwards

. I believe it gains you about 5-10HP not having it fitted, but dont quote me.... was more HP than noise in their case.