the diy for installing exhaust didnt quite state what type of lubricant is needed to get the stock cat off. Would some WD40 work for that? and what tools do i need to get it off? I tried using a screwdriver lying around but didnt work for me =/

well after you have unbolted it if it still does not want to jar lose then you can take some liquid wrench and spray it.. let set for a sec then gently try to tap it lose with a hammer. if that does not work... be less gentle with the hammer.