I researched this a ton. Micron, Micron, Micron.
Yoshis are real nice too. Scorpion's say their slip ons do not need remapping at all. From what I see you don't need to jet bikes with a slip on, but most recommend it. Scorpion's doesn't improve performance, just sound, that is why they advertise no jetting required.
2005 Honda CRF88RR - 2007 Honda CBR600RR