I will also add that wearing a helmet can actually increase the noise levels as the sound the air makes when rushing by can actually be amplified by the helmet surfaces. Most advocates of helmet usage also recommend wearing earplugs as well. I have done this on and off and can say that it makes a tremendous difference.
I know quite a few people who run loud pipes on their motorcycles that have substantial hearing loss because of it. Sounding cool is not worth it in my experience. The "loud pipes saves lives" argument IMO is not valid. Wearing brightly colored clothing has been more effective for me. They don't see you if you have the black pirate outfit on.