no biggie - i'm doing a sale right now till the end of the year. the link in my sig will have a payment link for the $23 sets. yours i believe is still at $25. i'll take the extra $2 though. basically i'm just eating shipping. $1.92 to be exact.
blocks off the air induction system (AIS), atleast i think thats what it stands for. click that link that justin posted, itll explain everything. basically blocks off the ports where the bike would recycle spent exhaust gases, and with a full exhaust/fuel controller, it wouldnt allow you to get a proper reading, therefore not allowing for a proper air/fuel ratio. also minimizes the decel popping.