I have the OEM exhaust on my FZ6 but when I started riding, initially I didn't use earplugs.
However I then tried some (they were giving them away for free at one of the Ride it Right events at Haslemere Fire Station) and realised that a) I could still hear what was going on around me and b) I didn't end up with ringing in my ears from the constant wind-blast, so now, unless I'm just riding around town, I will always wear them because I like my hearing!
(PS loud pipes don't save lives, defensive riding does!
)