Power loss.....How do I fix it???

[smitty's99]

Hello everbody. I'm new to the board. I have a question for you guys. I just changed my spark plugs in my 99' Superhawk and added a K&N air filter. I experienced hesitation and a loss in power while accelerating. I immediately switched back to my stock air filter. I regained most of the power, but the bike still doesn't feel as fast as it was before I changed over. My current mods include Erion Racing Stage 1 Dynojet kit and Erion racing slip-ons. Does anybody have any suggestions on what I could do to restore my power??

Thanks in advance, Art