For general clearance, not required. For a more accurate look and for Lancer approval...yes.
I've updated my helmet and used decals from Trooperbay, an MC snout (you can also pick these up from Don-Jarr), and then used the 3M bolt covers. For mine, I used a dremel to whittle the 3M-s down to just the round covers and then glued them on. Easy enough...