Rejetting’s only needed if you do a full exhaust replacement. You won’t need to rejet if all you change is the slip on. You can rejet if you want but you won’t see much of a performance difference. Although, you will have to ride the bike a while to really determine if you need to rejet. If you start back firing or loose power at higher gears, then those are signs that a rejetting is needed.
Edit: yeh, might i add, love my two bros. titanium m2 slip on. 
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If there’s anything more important than my ego
around, I want it caught and shot now…
