K&N Air Filter for the cheapest price I have seen yet:
[ame=http://www.amazon.com/gp/product/B002CP9WWI/ref=s9_simh_gw_p263_d0_i1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=0Y20V57TG1QRGGK9ZDP3&pf_rd_t=101&pf_rd_p=1389517282&pf_rd_i=507846]Amazon.com: K&N YA-6009 Yamaha High Performance Replacement Air Filter: Automotive[/ame]