I was wondering which of the cobra exhausts is the loudest: the jet system, the black megaphone system or the regular aluminum 4 stroke system?
Sound isnt an issue for me because i ride mostly in pits where people wont be bothered.

 

They're all loud pieces of crap.

Expect to gain lots of sound, and little to no performance with a Cobra pipe.

Your bike is already equipped with the loudest pipe available if that's what you're concerned with. Just remove the silencer from the headpipe, then you'll sound really cool.