Ok, I did some digging on this site to find out myself and really got an education on it.
The pair valve is designed to take some clean air from the airbox and add it to the exhaust to aid in the fluency of the exhaust (adds to back pressure). When you change to a performance exhaust, you have more air flow and that can cause the bike to backfire if the pair valve is not removed (loss of back pressure).
Brock's kit is designed to block the ports for the pair valve. His kit will give you specific instructions on how to remove the pair valve, how and which air box mod to do, and it should include a map for the mod, but I think his map is designed for his signature street exhaust.
Hope that helps.