looks good mate,
a lot better than my mates c2, he just made it look stupid.
i'd say no to an exhaust, im a noise maniac. I use Studio Monitors to listen to music at home and the bike is FOOKing loud, (ask Cold hand luke) but my mate did the exhaust on his c2, it wasnt a cheap one either, but it sounded a bit naff.
save the exhaust money for when u have a supercar!
(just my opinions)