Hello guys and girls, im new to riding and picked up my first bike 07 zzr600 a couple months ago. i have questions about jetting. i am looking at yoshimura rs-3 stainless bolt on muffler simply because it is the least expencive i can find that i have heard of. i called yoshimura and they claim its not needed if no other mods are done to it. although every shop i talk to say it is needed. Im looking to get advice from someone who has experianced this before and can help. Thanks a lot, I use this site often but i have never signed up until today.