I've been doing some research and I discovered that not all slip ons need to be rejetted. What I mean is that "some" slip ons will run perfectly fine after installation, where as some will require rejetting, it all depends on the particular slip on.
All slip ons say "does not require any tuning" well this is misleading, because even though it doesn't "Require" tuning, it will run slightly too lean without it. This is the case for most..
So, here's what I did, I contacted the seller for this Musarri
http://www.ebay.com/itm/08-13-Kawasa...f71d34&vxp=mtr
asking him will I need to rejet, will performance be disrupted, etc. etc. And i'm looking back for his answer, also I contacted some people on youtube who installed the slip on and asked them if they rejetted and if not did they notice any loss of power..
If all checks out I will order the exhaust asap and report back with my findings.
Please note: that my findings for this particular slip on do NOT reflect other slip ons.