After all that loud Jet engine noise the bikes don't seem that loud to me, but maybe I should start using earplugs too.
One thing to watch out for though Make sure your fingers are clean before putting them in. Motor Oil, Fiberglass dust, stuff like that gets on the earplugs and then inside your ears. Ears Hate old turbine oil & composite dust. After a while Ears will want some sort of medication applied to them after such abuse.