Hi, Im hoping this is the right area for posting this, soon find out I have a 2009 GSXR1000 currently doing some mods. Before each mod i have done i search the web for answers only to be more confused about the subject than when i started. Im wondering if there is anyone on this forum the has the mechanical no how and knowledge to answer what troubles me. I have read and re read different answers to my question "titled" with no real 100% confirmed result. The only firm answer i get is from the shop or the mechanic who i feel is sometimes trying to just sell me another peice of equipment i dont need. I have upgrade the exhaust from stock to Slip-on Jardine GP-1 with the cat still in place. (found that it had no change to the bike that i could notice.) Now i have recenlty purchased a high flow K&N air filter ($12 on ebay to cheap not to buy). With these two mods on the bike can i expect to be running lean on the A/F mixture or will it have no effect or minimal to the bike? Will i damage the bike if i run these items without putting a PC on it? By leaving the cat in place due to the slip-on's have i bypassed the need to tune the A/F mix? And due to always getting answers that give me no conclusive answers Id prefer answers from people who have experience in this or have done similar mods them self. Mechanics that no the answer and arn't just trying to sell me something Thanks and i look forward to your responses.