I don't remember the instructions mentioning not to fit Gaskets - I certainly did when I installed my Serket Taper (re-used the originals as the bike was fairly new) and had no issues at that junction.
Probably best to call Scorpion to confirm though (they offer technical advice over the phone).
Do note, when installing Gaskets, that they are designed to be installed in a particular orientation (if you look carefully, you should see that one side of the Gasket is flat and the other very slightly curved).